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Apollo_7 | Apollo 7 was an October 1968 human spaceflight mission carried out by the United States . It was the first mission in the United States ' Apollo program to carry a crew into space . It was also the first U.S. spaceflight to carry astronauts since the flight of Gemini XII in November 1966 . The AS-204 mission , also known as `` Apollo 1 '' , was intended to be the first manned flight of the Apollo program . It was scheduled to launch in February 1967 , but a fire in the cabin during a January 1967 test killed the crew . Manned flights were then suspended for 21 months , while the cause of the accident was investigated and improvements made to the spacecraft and safety procedures , and unmanned test flights of the Saturn V rocket and Apollo Lunar Module were made . Apollo 7 fulfilled Apollo 1 's mission of testing the Apollo Command/Service Module ( CSM ) in low Earth orbit . The Apollo 7 crew was commanded by Walter M. Schirra , with senior pilot / navigator Donn F. Eisele , and pilot / systems engineer R. Walter Cunningham . Official crew titles were made consistent with those that would be used for the manned lunar landing missions : Eisele was Command Module Pilot and Cunningham was Lunar Module Pilot . Their mission was Apollo 's ` C ' mission , an 11-day Earth-orbital test flight to check out the redesigned Block II CSM with a crew on board . It was the first time a Saturn IB vehicle put a crew into space ; Apollo 7 was the first three-person American space mission , and the first to include a live TV broadcast from an American spacecraft . It was launched on October 11 , 1968 , from what was then known as Cape Kennedy Air Force Station , Florida . Despite tension between the crew and ground controllers , the mission was a complete technical success , giving NASA the confidence to send Apollo 8 into orbit around the Moon two months later . The flight would prove to be the final space flight for all of its three crew members -- and the only one for both Cunningham and Eisele -- when it splashed down in the Atlantic Ocean on October 22 , 1968 . It was also the only manned launch from Launch Complex 34 , as well as the last launch from the complex . |
Anoxia | The term anoxia means a total depletion in the level of oxygen , an extreme form of hypoxia or `` low oxygen '' . The terms anoxia and hypoxia are used in various contexts : Anoxic waters , sea water , fresh water or groundwater that are depleted of dissolved oxygen Anoxic event , when the Earth 's oceans become completely depleted of oxygen below the surface levels Euxinic , anoxic conditions in the presence of hydrogen sulfide Hypoxia ( environmental ) , low oxygen conditions Hypoxia ( medical ) , when the body or a region of the body is deprived of adequate oxygen supply Cerebral anoxia , when the brain is completely deprived of oxygen , an extreme form of cerebral hypoxia |
Antarctic_Plate | The Antarctic Plate is a tectonic plate containing the continent of Antarctica and extending outward under the surrounding oceans . After breakup from Gondwana ( the southern part of the supercontinent Pangea ) , the Antarctic plate began moving the continent of Antarctica south to its present isolated location causing the continent to develop a much colder climate . The Antarctic Plate is bounded almost entirely by extensional mid-ocean ridge systems . The adjoining plates are the Nazca Plate , the South American Plate , the African Plate , the Indo-Australian Plate , the Pacific Plate , and , across a transform boundary , the Scotia Plate . The Antarctic plate has an area of about 60,900,000 km2 . It is the Earth 's fifth largest plate . The Antarctic plate 's movement is estimated to be at least 1 cm per year towards the Atlantic Ocean . |
Antarctic_sea_ice | Antarctic sea ice is the sea ice of the Southern Ocean . It extends far north in winter and retreats almost to the coastline each summer . Sea ice is frozen seawater that is usually less than a few meters thick . This is in contrast to ice shelves , which are formed by glaciers , float in the sea , and are up to a kilometer thick . There are two subdivisions of sea ice : fast ice , which is attached to land ; and ice floes , which are not . Sea ice in the Southern Ocean melts from the bottom instead of from the surface like Arctic ice because it is covered in snow . As a result , melt ponds are rarely observed . On average , Antarctic sea ice is younger , thinner , warmer , saltier , and more mobile than Arctic sea ice . Due to its inaccessibility , it is not as well-studied as Arctic ice . |
Antarctandes | The Antarctandes ( Antartandes in Spanish ) , also known as the Antarctic Peninsula cordillera , is the mountain range that is located in the axis of the Antarctic Peninsula and can be considered the continuation of the Andes mountains in the Antarctic continent . According to this theory the Andes start at the border between Colombia and Venezuela , submerge in the Atlantic ocean to the east of Tierra del Fuego forming the underwater mountain range Scotia Arc and reappear in stretches in the Shag Rocs , South Georgia and the South Sandwich Islands , South Orkney and South Shetland islands , continuing afterwards on the Antarctic peninsula . Chile calls this Tierra de O'Higgins and Argentina , Tierra de San Martín . The highest mountain of the Antartandes is Mount Coman ( 3,657 m ) in the segment called the Eternity Range ; Mount Hope ( 2,860 m ) also stands out . Southwest of the Antartandes -RSB- are the Ellsworth Mountains , a low mountain range much-covered by glaciers , and another big Antarctic mountain range , the Transantarctic Mountains . In these , more exactly in the segment called the Diamond Mountains , is the nunatak Mount Chiriguano ( 3,660 m ) . Beyond this , the Antarctic Plateau extends to the South Pole . The Antartandes is claimed by Argentina ( Argentine Antarctica ) , Chile ( Chilean Antarctic Territory ) and the United Kingdom ( British Antarctic Territory ) , but all these claims are frozen by Article 4 of the Antarctic Treaty System . |
Aquaculture | Aquaculture , also known as aquafarming , is the farming of fish , crustaceans , molluscs , aquatic plants , algae , and other aquatic organisms . Aquaculture involves cultivating freshwater and saltwater populations under controlled conditions , and can be contrasted with commercial fishing , which is the harvesting of wild fish . Mariculture refers to aquaculture practiced in marine environments and in underwater habitats . According to the FAO , aquaculture `` Farming implies some form of intervention in the rearing process to enhance production , such as regular stocking , feeding , protection from predators , etc. . Farming also implies individual or corporate ownership of the stock being cultivated . '' The reported output from global aquaculture operations in 2014 supplied over one half of the fish and shellfish that is directly consumed by humans ; however , there are issues about the reliability of the reported figures . Further , in current aquaculture practice , products from several pounds of wild fish are used to produce one pound of a piscivorous fish like salmon . Particular kinds of aquaculture include fish farming , shrimp farming , oyster farming , mariculture , algaculture ( such as seaweed farming ) , and the cultivation of ornamental fish . Particular methods include aquaponics and integrated multi-trophic aquaculture , both of which integrate fish farming and plant farming . |
Archipelago | An archipelago ( -LSB- ɑːrkᵻˈpɛləɡoʊ -RSB- ) , sometimes called an island group or island chain , is a chain , cluster or collection of islands . The word archipelago is derived from the Greek ἄρχι - -- arkhi - ( `` chief '' ) and πέλαγος -- pélagos ( `` sea '' ) through the Italian arcipelago . In Italian , possibly following a tradition of antiquity , the Archipelago ( from medieval Greek * ἀρχιπέλαγος and Latin archipelagus ) was the proper name for the Aegean Sea and , later , usage shifted to refer to the Aegean Islands ( since the sea is remarkable for its large number of islands ) . It is now used to refer to any island group or , sometimes , to a sea containing a small number of scattered islands . |
Arctic_resources_race | The Arctic resources race refers to the competition between global entities for newly available natural resources in the Arctic . As the ice in the Arctic melts at a record rate and the sea ice extent continues to decrease due to global climate change , the Arctic waters become more navigable and Arctic resources -- such as oil and gas , minerals , fish , as well as tourism and new trade routes -- are becoming more accessible . Under the United Nations Convention of the Law of the Sea , five nations have the legal right to exploit the Arctic 's natural resources within their exclusive economic zones : Canada , Russia , Denmark , Norway , and the United States ( though the U.S. has yet to ratify the treaty , it considers the treaty to be customary international law and abides by it ) . The Arctic region and its resources have recently been at the center of controversy and pose potential conflicts between nations that have differing opinions of how to manage the area , including conflicting territorial claims . In addition , the Arctic region is home to an estimated 400,000 indigenous people . If the ice continues to melt at the current rate , then these indigenous people are at risk of being displaced . The acceleration of ice depletion will contribute to climate change as a whole : melting ice releases methane , ice reflects incoming solar radiation , and without it will cause the ocean to absorb more radiation ( albedo effect ) , heating up the water causing more ocean acidification , and melting ice will cause a rise in sea level . |
Arctic_ecology | Arctic ecology is the scientific study of the relationships between biotic and abiotic factors in the arctic , the region north of the Arctic Circle ( 66 33 ' ) . This is a region characterized by stressful conditions as a result of extreme cold , low precipitation , a limited growing season ( 50 -- 90 days ) and virtually no sunlight throughout the winter . The Arctic consists of taiga ( or boreal forest ) and tundra biomes , which also dominate very high elevations , even in the tropics . Sensitive ecosystems exist throughout the Arctic region , which are being impacted dramatically by global warming . The earliest inhabitants of the Arctic were the Neanderthals . Since then , many indigenous populations have inhabited the region , which continues to this day . Since the early 1900s , when Vilhjalmur Stefansson led the first major Canadian Arctic Expedition , the Arctic has been a valued area for ecological research . In 1946 , The Arctic Research Laboratory was established in Point Barrow , Alaska under the contract of the Office of Naval Research . This launched an interest in exploring the Arctic examining animal cycles , permafrost and the interactions between indigenous peoples and the Arctic ecology . During the Cold War , the Arctic became a place where the United States , Canada , and the Soviet Union performed significant research that has been essential to the study of climate change in recent years . A major reason why research in the Arctic is essential for the study of climate change is because the effects of climate change will be felt more quickly and more drastically in higher latitudes of the world as above average temperatures are predicted for Northwest Canada and Alaska . From an anthropological point of view , researchers study the native Inuit peoples of Alaska as they have become extremely accustomed to adapting to ecological and climate variability . |
Andalusia | Andalusia ( Andalucia ) ( -LSB- ˌændəˈluːsiə , _ - ziə , _ - ʒə -RSB- Andalucía -LSB- andaluˈθi.a , - si.a -RSB- ) is an autonomous community in southern Spain . It is the most populated and the second largest in area of the autonomous communities in the country . The Andalusian autonomous community is officially recognised as `` historical nationality '' . The territory is divided into eight provinces : Almería , Cádiz , Córdoba , Granada , Huelva , Jaén , Málaga and Seville . Its capital is the city of Seville ( Spanish : Sevilla ) . Spain does not recognize British sovereignty over Gibraltar due to not faithfully fulfilling Article X of the 1713 Treaty of Utrecht . Therefore , according to Spain , Gibraltar forms part of the Province of Cadiz . Andalusia is in the south of the Iberian peninsula , in south-western Europe , immediately south of the autonomous communities of Extremadura and Castilla-La Mancha ; west of the autonomous community of Murcia and the Mediterranean Sea ; east of Portugal and the Atlantic Ocean ; and north of the Mediterranean Sea and the Strait of Gibraltar . Andalusia is the only European region with both Mediterranean and Atlantic coastlines . The small British overseas territory of Gibraltar shares a three-quarter-mile land border with the Andalusian province of Cádiz at the eastern end of the Strait of Gibraltar . The main mountain ranges of Andalusia are the Sierra Morena and the Baetic System , consisting of the Subbaetic and Penibaetic Mountains , separated by the Intrabaetic Basin . In the north , the Sierra Morena separates Andalusia from the plains of Extremadura and Castile -- La Mancha on Spain 's Meseta Central . To the south the geographic subregion of Upper Andalusia lies mostly within the Baetic System , while Lower Andalusia is in the Baetic Depression of the valley of the Guadalquivir . The name `` Andalusia '' is derived from the Arabic word Al-Andalus . The region 's history and culture have been influenced by the native Iberians , Phoenicians , Carthaginians , Greeks , Romans , Vandals , Visigoths , Byzantines , Jews , Romani , Muslim Moors and the Castilian and other Christian North Iberian nationalities who reconquered and settled the area in the latter phases of the Reconquista , and includes an intense relationship with Naples , Italy . Andalusia has been a traditionally agricultural region , compared to the rest of Spain and the rest of Europe . However , the growth of the community especially in the sectors of industry and services was above average in Spain and higher than many communities in the Eurozone . The region has , however , a rich culture and a strong cultural identity . Many cultural phenomena that are seen internationally as distinctively Spanish are largely or entirely Andalusian in origin . These include flamenco and , to a lesser extent , bullfighting and Hispano-Moorish architectural styles . Andalusia 's hinterland is the hottest area of Europe , with cities like Córdoba and Seville averaging above 36 ° C ( 97 ° F ) in summer high temperatures . Late evening temperatures can sometimes stay around 35 ° C ( 95 ° F ) until close to midnight , with daytime highs of over 40 ° C ( 104 ° F ) common . Seville also has the highest average annual temperature in mainland Spain and mainland Europe ( 19.2 ° C ) , closely followed by Almería ( 19.1 ° C ) . |
Arctic_policy_of_Norway | Arctic Policy of Norway is Norway 's foreign relations with other Arctic countries , and Norway 's government policies on issues occurring within the geographic boundaries of `` the Arctic '' or related to the Arctic or its peoples . Since Norway is itself an Arctic nation , the Arctic Policy of Norway includes its domestic policies as regards the Norwegian Arctic region . In Norway , development in the High North , including the Arctic , has been the Government 's highest foreign policy priority since 2005 . The Norwegian Government 's High North strategy was released December 1 , 2006 . On March 12 , 2009 Norway released the report `` New Building Blocks in the North '' which identifies seven priority areas : 1 ) climate and the environment ; 2 ) monitoring-emergency response-maritime safety in northern waters ; 3 ) sustainable development of offshore petroleum and renewable marine resources ; 4 ) onshore business development ; 5 ) infrastructure ; 6 ) sovereignty and cross-border cooperation ; and 7 ) the culture and livelihoods of indigenous peoples . In the 2011 central government budget , a total of NOK 1.2 billion was set aside for initiatives in the High North , a significant portion of which was earmarked for research . The Norwegian Government intends to present an updated version of its strategy ( `` Towards the North '' ) soon . |
Arch_Coal | Arch Coal is an American coal mining and processing company . The company mines , processes , and markets bituminous and sub-bituminous coal with low sulfur content in the United States . Arch Coal is the second largest supplier of coal in the U.S. behind Peabody Energy . The company supplies 15 % of the domestic market . Demand comes mainly from generators of electricity . Arch Coal operates 32 active mines and controls approximately 5.5 billion tons of proven and probable coal reserves , located in Central Appalachia , the Powder River Basin , Illinois basin and the Western Bituminous regions . The company operates mines in Colorado , Illinois , Kentucky , Utah , Virginia , West Virginia and Wyoming , and is headquartered in St. Louis , Missouri . The company sells a substantial amount of its coal to producers of electric power , steel producers and industrial facilities . |
Arctic_policy_of_Canada | The Arctic policy of Canada includes both the foreign policy of Canada in regard to the Arctic region and Canada 's domestic policy towards its Arctic territories . This includes the devolution of powers to the territories . Canada 's Arctic policy includes the plans and provisions of these regional governments . It encompasses the exercise of sovereignty , social and economic development , the protection of the environment , and the improving and devolving of governance . Canada , along with the 7 other Arctic nations , is a member of the Arctic Council . On August 23 , 2012 , Prime Minister Stephen Harper announced that Nunavut MP Leona Aglukkaq would serve as chair of the Arctic Council when Canada assumed the Chairmanship from Sweden in May 2013 . Along with its mainland in the upper regions of North America , Canada claims sovereignty over the related continental shelf and the Arctic Archipelago . It considers the waters between the islands of the Archipelago to be Canadian Internal Waters . The United States considers those to be international waters . Canada has more Arctic land mass than any other country . This land is included within the administrative regions of the Northwest Territories , Nunavut , and Yukon . As of 2011 , approximately 107,265 Canadians live in the Arctic . |
Arctic_Archipelago_Marine_Ecozone_(CEC) | The Arctic Archipelago Marine Ecozone , as defined by the Commission for Environmental Cooperation ( CEC ) , is a marine ecozone in the Canadian Arctic , encompassing Hudson Bay , James Bay , the internal waters and some shores of the islands in the Canadian Arctic Archipelago , and the shores of the territories , northern Ontario and western Quebec . Early exploration of these waters by Europeans were conducted to find a passage to the Orient , now referred to as the Northwest Passage . It is inextricably tied to the terrestrial ecozones of the Arctic Cordillera , Northern Arctic , Southern Arctic , Hudson Plains , Taiga Shield , Taiga Plains , and Taiga Cordillera , as well as the marine ecozones of the Arctic Basin Marine and Northwest Atlantic Marine . |
Apartment | An apartment ( American English ) , flat ( British English ) or unit ( Australian English ) is a self-contained housing unit ( a type of residential real estate ) that occupies only part of a building , generally on a single level without stairs . Such a building may be called an apartment building , apartment complex , flat complex , block of flats , tower block , high-rise or , occasionally mansion block ( in British English ) , especially if it consists of many apartments for rent . In Scotland , it is called a block of flats or , if it is a traditional sandstone building , a tenement , which has a pejorative connotation elsewhere . Apartments may be owned by an owner/occupier , by leasehold tenure or rented by tenants ( two types of housing tenure ) . |
Aqua_(satellite) | Aqua ( EOS PM-1 ) is a multi-national NASA scientific research satellite in orbit around the Earth , studying the precipitation , evaporation , and cycling of water . It is the second major component of the Earth Observing System ( EOS ) preceded by Terra ( launched 1999 ) and followed by Aura ( launched 2004 ) . The name `` Aqua '' comes from the Latin word for water . The satellite was launched from Vandenberg Air Force Base on May 4 , 2002 , aboard a Delta II rocket . Aqua is on a Sun-synchronous orbit . It flies as the second in the satellite formation called the `` A Train '' with several other satellites ( Aura , CALIPSO , CloudSat , OCO-2 , the French PARASOL , and the Japanese GCOM W1 ) . |
Arctic_realm | The Arctic realm is one of the planet 's twelve marine realms , as designated by the WWF and Nature Conservancy . It includes the coastal regions and continental shelves of the Arctic Ocean and adjacent seas , including the Arctic Archipelago , Hudson Bay , and the Labrador Sea of northern Canada , the seas surrounding Greenland , the northern and eastern coasts of Iceland , and the eastern Bering Sea . The Arctic realm transitions to the Temperate Northern Atlantic realm in the Atlantic Basin , and the Temperate Northern Pacific realm in the Pacific Basin . |
Arctic_oscillation | The Arctic oscillation ( AO ) or Northern Annular Mode/Northern Hemisphere Annular Mode ( NAM ) is an index ( which varies over time with no particular periodicity ) of the dominant pattern of non-seasonal sea-level pressure variations north of 20N latitude , and it is characterized by pressure anomalies of one sign in the Arctic with the opposite anomalies centered about 37 -- 45N . The AO is believed by climatologists to be causally related to , and thus partially predictive of , weather patterns in locations many thousands of miles away , including many of the major population centers of Europe and North America . NASA climatologist Dr. James E. Hansen explained the mechanism by which the AO affects weather at points so distant from the Arctic , as follows : `` The degree to which Arctic air penetrates into middle latitudes is related to the AO index , which is defined by surface atmospheric pressure patterns . When the AO index is positive , surface pressure is low in the polar region . This helps the middle latitude jet stream to blow strongly and consistently from west to east , thus keeping cold Arctic air locked in the polar region . When the AO index is negative , there tends to be high pressure in the polar region , weaker zonal winds , and greater movement of frigid polar air into middle latitudes . '' This zonally symmetric seesaw between sea level pressures in polar and temperate latitudes was first identified by Edward Lorenz and named in 1998 by David W.J. Thompson and John Michael Wallace . The North Atlantic oscillation ( NAO ) is a close relative of the AO and there exist arguments about whether one or the other is more fundamentally representative of the atmosphere 's dynamics ; Ambaum et al. argue that the NAO can be identified in a more physically meaningful way . Over most of the past century , the Arctic Oscillation alternated between its positive and negative phases . Starting in the 1970s the oscillation has trended to more of a positive phase when averaged using a 60-day running mean , though it has trended to a more neutral state in the last decade . The oscillation still fluctuates stochastically between negative and positive values on daily , monthly , seasonal and annual time scales , although , despite its stochastic nature , meteorologists have attained high levels of predictive accuracy in recent times , at least for the shorter term forecasts . ( The correlation between actual observations and the 7-day mean GFS ensemble AO forecasts is approximately 0.9 , a figure at the high end for that statistic . ) The National Snow and Ice Data Center describes the effects of the AO in some detail : `` In the positive phase , higher pressure at midlatitudes drives ocean storms farther north , and changes in the circulation pattern bring wetter weather to Alaska , Scotland and Scandinavia , as well as drier conditions to the western United States and the Mediterranean . In the positive phase , frigid winter air does not extend as far into the middle of North America as it would during the negative phase of the oscillation . This keeps much of the United States east of the Rocky Mountains warmer than normal , but leaves Greenland and Newfoundland colder than usual . Weather patterns in the negative phase are in general `` opposite '' to those of the positive phase . '' Climatologists are now routinely invoking the Arctic Oscillation in their official public explanations for extremes of weather . The following statement from the National Oceanic and Atmospheric Administration 's National Climatic Data Center : State of the Climate December 2010 which uses the phrase `` negative Arctic Oscillation '' four times , is very representative of this increasing tendency : `` Cold arctic air gripped western Europe in the first three weeks of December . Two major snowstorms , icy conditions , and frigid temperatures wreaked havoc across much of the region ... The harsh winter weather was attributed to a negative Arctic Oscillation , which is a climate pattern that influences weather in the Northern Hemisphere . A very persistent , strong ridge of high pressure , or ` blocking system ' , near Greenland allowed cold Arctic air to slide south into Europe . Europe was not the only region in the Northern Hemisphere affected by the Arctic Oscillation . A large snow storm and frigid temperatures affected much of the Midwest United States on December 10 -- 13 ... '' A further , quite graphic illustration of the effects of the negative phase of the oscillation occurred in February 2010 . In that month , the Arctic Oscillation reached its most negative monthly mean value , − 4.266 , in the entire post-1950 era ( the period of accurate record-keeping ) . That month was characterized by three separate historic snowstorms that occurred in the mid-Atlantic region of the United States . The first storm dumped 25 in on Baltimore , Maryland , on February 5 -- 6 , and then a second storm dumped 19.5 in on February 9 -- 10 . In New York City , a separate storm deposited 20.9 in on February 25 -- 26 . This kind of snowstorm activity is as anomalous and extreme as the negative AO value itself . Similarly , the greatest negative value for the AO since 1950 in January was − 3.767 in 1977 , which coincided with the coldest mean January temperature in New York City , Washington , D.C. , Baltimore , and many other mid-Atlantic locations in that span of time . And though the January AO has been negative only 60.6 % of the time between 1950 and 2010 , 9 of the 10 coldest Januarys in New York City since 1950 have coincided with negative AOs . However , the correlation between sharply negative Arctic Oscillations and excessive winter cold and snow in regions vulnerable in that way to these negative AOs should not be overstated . It is by no means a simple , one-to-one equivalence . An extreme Arctic Oscillation does not necessarily mean extreme weather will occur . For example , since 1950 , eight out of the 10 coldest Januarys in New York did not coincide with the 10 lowest January AO values . And the fourth warmest January there since 1950 coincided with one of those 10 most negative AOs . So , although many climatologists believe that the Arctic Oscillation affects the probability of certain weather events occurring in certain places , the heightened chance of a phenomenon by no means assures it , nor does the lessened likelihood exclude it . Further , the precise value of the AO index only imperfectly reflects the severity of the weather associated with it . |
Arctic_Circle_(organization) | The Arctic Circle is a nonprofit organization introduced by President Ólafur Ragnar Grímsson of Iceland on April 15 , 2013 , at the National Press Club in Washington . The organization 's mission is to facilitate dialogue among political and business leaders , environmental experts , scientists , indigenous representatives , and other international stakeholders to address issues facing the Arctic as a result of climate change and melting sea ice . The organization is led by Ólafur , who serves as chairman of the honorary board , and by Alaska Dispatch publisher and Arctic Imperative Summit founder Alice Rogoff , who chairs the advisory board . |
Arctic_dipole_anomaly | The Arctic dipole anomaly is a pressure pattern characterized by high pressure on the arctic regions of North America , and a low pressure on the Eurasia region . This pattern sometimes replaces the Arctic oscillation and the North Atlantic Oscillation . It was observed for the first time in the first decade of 2000s and is perhaps linked to recent climate change . The Arctic dipole lets more southern winds into the Arctic ocean resulting in more ice melting . The summer 2007 event played an important role in the record low sea ice extent which was recorded in September . The Arctic dipole has also been linked to changes in arctic circulation patterns that cause drier winters in Northern Europe , but much wetter winters in Southern Europe and colder winters in East Asia , Europe and the eastern half of North America . |
Arctic_methane_emissions | Arctic methane release is the release of methane from seas and soils in permafrost regions of the Arctic . While a long-term natural process , it is exacerbated by global warming . This results in a positive feedback effect , as methane is itself a powerful greenhouse gas . The Arctic region is one of the many natural sources of the greenhouse gas methane . Global warming accelerates its release , due to both release of methane from existing stores , and from methanogenesis in rotting biomass . Large quantities of methane are stored in the Arctic in natural gas deposits , permafrost , and as undersea clathrates . Permafrost and clathrates degrade on warming , thus large releases of methane from these sources may arise as a result of global warming . Other sources of methane include submarine taliks , river transport , ice complex retreat , submarine permafrost and decaying gas hydrate deposits . Concentrations in the Arctic atmosphere are higher by 8 -- 10 % than that in the Antarctic atmosphere . During cold glacier epochs , this gradient decreases to practically insignificant levels . Land ecosystems are considered the main sources of this asymmetry , although it has been suggested that `` the role of the Arctic Ocean is significantly underestimated . '' Soil temperature and moisture levels have been found to be significant variables in soil methane fluxes in tundra environments . |
Arctic_Alaska | Arctic Alaska or Far North Alaska is a region of the U.S. state of Alaska generally referring to the northern areas on or close to the Arctic Ocean . It commonly includes North Slope Borough , Northwest Arctic Borough , Nome Census Area , and is sometimes taken to include parts of the Yukon-Koyukuk Census Area . Some notable towns there include Prudhoe Bay , Barrow , Kotzebue , Nome , and Galena . Most of these communities have no highways and can only be reached by aircraft or snowmobile in good weather . Originally inhabited by various Alaska Native groups living off hunting , whaling , or salmon fishing , modern settlement in Arctic Alaska was driven first by discoveries of gold and later on by the extraction of petroleum . The ecosystem consists largely of tundra covering mountain ranges and coastal plains which are home to bears , wolves , sheep , oxen , reindeer , and numerous species of birds , indeed the north coast has been defined as the Arctic coastal tundra ecoregion . Arctic Alaska is also the location of the Arctic National Wildlife Refuge , Gates of the Arctic National Park and Preserve , and the National Petroleum Reserve-Alaska . The Arctic experiences midnight sun in the summer and polar night in the winter . |
Arktika_2007 | Arktika 2007 ( Российская полярная экспедиция '' Арктика-2007 '' ) was a 2007 expedition in which Russia performed the first ever crewed descent to the ocean bottom at the North Pole , as part of research related to the 2001 Russian territorial claim , one of many territorial claims in the Arctic , made possible , in part , because of Arctic shrinkage . As well as dropping a titanium tube containing the Russian flag , the submersibles collected specimens of Arctic flora and fauna and apparently recorded video of the dives . The `` North Pole-35 '' ( abbreviated as `` NP-35 '' ) manned drifting ice station was established . On January 10 , 2008 three of expedition members who performed the descent to the ocean bottom at the North Pole , Anatoly Sagalevich , Yevgeny Chernyaev and Artur Chilingarov were awarded titles Hero of the Russian Federation `` for courage and heroism showed in extremal conditions and successful completion of High-Latitude Arctic Deep-Water Expedition . '' |
Antilles_Current | The Antilles Current is a highly variable surface ocean current of warm water that flows northwesterly past the island chain that separates the Caribbean Sea and the Atlantic Ocean . The current results from the flow of the Atlantic North Equatorial Current . This current completes the clockwise - cycle or convection ( North Atlantic Gyre ) that is located in the Atlantic Ocean . It runs north of Puerto Rico , Hispaniola and Cuba , but south to the Bahamas , facilitating maritime communication from across the Atlantic into these islands ' northern coasts , and connecting to the Gulf Stream at the intersection of the Florida Strait . Because of its non-dominant pace and rich-nutrient waters , fishermen across the Caribbean Islands use it to fish . It moves almost parallel to the also rich-nutrient Caribbean Current which flows south of Puerto Rico and Cuba , and over Colombia and Venezuela . |
Antarctic_ice_sheet | The Antarctic ice sheet is one of the two polar ice caps of the Earth . It covers about 98 % of the Antarctic continent and is the largest single mass of ice on Earth . It covers an area of almost 14 e6km2 and contains 26.5 e6km3 of ice . Approximately 61 percent of all fresh water on the Earth is held in the Antarctic ice sheet , an amount equivalent to about 58 m of sea-level rise . In East Antarctica , the ice sheet rests on a major land mass , but in West Antarctica the bed can extend to more than 2,500 m below sea level . Much of the land in this area would be seabed if the ice sheet were not there . In contrast to the melting of the Arctic sea ice , sea ice around Antarctica was expanding . The reasons for this are not fully understood , but suggestions include the climatic effects on ocean and atmospheric circulation of the ozone hole , and/or cooler ocean surface temperatures as the warming deep waters melt the ice shelves . |
Antarctic_Circle | The Antarctic Circle is the most southerly of the five major circles of latitude that mark maps of the Earth . The region south of this circle is known as the Antarctic , and the zone immediately to the north is called the Southern Temperate Zone . South of the Antarctic Circle , the sun is above the horizon for 24 continuous hours at least once per year ( and therefore visible at midnight ) and ( at least partially ) below the horizon for 24 continuous hours at least once per year ( and therefore not fully visible at noon ) ; this is also true within the equivalent polar circle in the Northern Hemisphere , the Arctic Circle . The position of the Antarctic Circle is not fixed ; as of , it runs south of the Equator . Its latitude depends on the Earth 's axial tilt , which fluctuates within a margin of 2 ° over a 40,000-year period , due to tidal forces resulting from the orbit of the Moon . Consequently , the Antarctic Circle is currently drifting southwards at a speed of about 15 m per year . |
Antarctica | Antarctica ( UK English -LSB- ænˈtɑːktɪkə -RSB- or -LSB- ænˈtɑːtɪkə -RSB- , US English -LSB- æntˈɑːrktɪkə -RSB- ) is Earth 's southernmost continent . It contains the geographic South Pole and is situated in the Antarctic region of the Southern Hemisphere , almost entirely south of the Antarctic Circle , and is surrounded by the Southern Ocean . At 14000000 km2 , it is the fifth-largest continent . For comparison , Antarctica is nearly twice the size of Australia . About 98 % of Antarctica is covered by ice that averages 1.9 km in thickness , which extends to all but the northernmost reaches of the Antarctic Peninsula . Antarctica , on average , is the coldest , driest , and windiest continent , and has the highest average elevation of all the continents . Antarctica is a desert , with annual precipitation of only 200 mm ( 8 in ) along the coast and far less inland . The temperature in Antarctica has reached − 89.2 ° C ( − 128.6 ° F ) , though the average for the third quarter ( the coldest part of the year ) is − 63 ° C ( − 81 ° F ) . Anywhere from 1,000 to 5,000 people reside throughout the year at the research stations scattered across the continent . Organisms native to Antarctica include many types of algae , bacteria , fungi , plants , protista , and certain animals , such as mites , nematodes , penguins , seals and tardigrades . Vegetation , where it occurs , is tundra . Although myths and speculation about a Terra Australis ( `` Southern Land '' ) date back to antiquity , Antarctica is noted as the last region on Earth in recorded history to be discovered and colonised by humans , being only first sighted in 1820 by the Russian expedition of Fabian Gottlieb von Bellingshausen and Mikhail Lazarev on Vostok and Mirny , who sighted the Fimbul ice shelf . The continent , however , remained largely neglected for the rest of the 19th century because of its hostile environment , lack of easily accessible resources , and isolation . In 1895 , the first confirmed landing was conducted by a team of Norwegians . Antarctica is a de facto condominium , governed by parties to the Antarctic Treaty System that have consulting status . Twelve countries signed the Antarctic Treaty in 1959 , and thirty-eight have signed it since then . The treaty prohibits military activities and mineral mining , prohibits nuclear explosions and nuclear waste disposal , supports scientific research , and protects the continent 's ecozone . Ongoing experiments are conducted by more than 4,000 scientists from many nations . |
Antarctica_cooling_controversy | An apparent contradiction in the observed cooling behavior of Antarctica between 1966 and 2000 became part of the public debate in the global warming controversy , particularly between advocacy groups of both sides in the public arena including politicians , as well as the popular media . In his novel State of Fear , Michael Crichton asserted that the Antarctic data contradict global warming . The few scientists who have commented on the supposed controversy state that there is no contradiction , while the author of the paper whose work inspired Crichton 's remarks has said that Crichton `` misused '' his results . There is no similar controversy within the scientific community , as the small observed changes in Antarctica are consistent with the small changes predicted by climate models , and because the overall trend since comprehensive observations began is now known to be one of warming . At the South Pole , where some of the strongest cooling trends were observed between the 1950s and 1990s , the mean trend is flat from 1957 through 2013 . |
Aral_Sea | The Aral Sea was an endorheic lake lying between Kazakhstan ( Aktobe and Kyzylorda Regions ) in the north and Uzbekistan ( Karakalpakstan autonomous region ) in the south . The name roughly translates as `` Sea of Islands '' , referring to over 1,100 islands that once dotted its waters ; in the Turkic languages aral means `` island , archipelago '' . The Aral Sea drainage basin encompasses Uzbekistan and parts of Tajikistan , Turkmenistan , Kyrgyzstan , Kazakhstan , Afghanistan and Pakistan . Formerly one of the four largest lakes in the world with an area of 68,000 km2 , the Aral Sea has been steadily shrinking since the 1960s after the rivers that fed it were diverted by Soviet irrigation projects . By 1997 , it had declined to 10 % of its original size , splitting into four lakes -- the North Aral Sea , the eastern and western basins of the once far larger South Aral Sea , and one smaller lake between the North and South Aral Seas . By 2009 , the southeastern lake had disappeared and the southwestern lake had retreated to a thin strip at the western edge of the former southern sea ; in subsequent years , occasional water flows have led to the southeastern lake sometimes being replenished to a small degree . Satellite images taken by NASA in August 2014 revealed that for the first time in modern history the eastern basin of the Aral Sea had completely dried up . The eastern basin is now called the Aralkum Desert . In an ongoing effort in Kazakhstan to save and replenish the North Aral Sea , a dam project was completed in 2005 ; in 2008 , the water level in this lake had risen by 12 m compared to 2003 . Salinity has dropped , and fish are again found in sufficient numbers for some fishing to be viable . The maximum depth of the North Aral Sea is 42 m . The shrinking of the Aral Sea has been called `` one of the planet 's worst environmental disasters '' . The region 's once-prosperous fishing industry has been essentially destroyed , bringing unemployment and economic hardship . The Aral Sea region is also heavily polluted , with consequential serious public health problems . UNESCO added the historical documents concerning the development of the Aral Sea to its Memory of the World Register as a unique resource to study this `` environmental tragedy . '' |
Argo_(oceanography) | Argo is an international program that uses profiling floats to observe temperature , salinity , currents , and , recently , bio-optical properties in the Earth 's oceans ; it has been operational since the early 2000s . The real-time data it provides is used in climate and oceanographic research . A special research interest is to quantify the ocean heat content ( OHC ) . The Argo fleet consists of almost 4000 drifting `` Argo floats '' ( as profiling floats used by the Argo program are often called ) deployed worldwide . Each float weighs 20 -- 30 kg . In most cases probes drift at a depth of 1000 metres ( the so-called parking depth ) and , every 10 days , by changing their buoyancy , dive to a depth of 2000 metres and then move to the sea-surface , measuring conductivity and temperature profiles as well as pressure . From these , salinity and density can be calculated . Seawater density is important in determining large-scale motions in the ocean . Average current velocities at 1000 metres are directly measured by the distance and direction a float drifts while parked at that depth , which is determined by GPS or Argos system positions at the surface . The data are transmitted to shore via satellite , and are freely available to everyone , without restrictions . The Argo program is named after the Greek mythical ship Argo to emphasize the complementary relationship of Argo with the Jason satellite altimeters . |
Aronia | Aronia is a genus of deciduous shrubs , the chokeberries , in the family Rosaceae native to eastern North America and most commonly found in wet woods and swamps . The genus is usually considered to contain two or three species , one of which is naturalized in Europe . A fourth form that has long been cultivated under the name Aronia is now considered to be an intergeneric hybrid , Sorbaronia mitschurinii . Chokeberries are cultivated as ornamental plants and as food products . The sour berries can be eaten raw off the bush , but are more frequently processed . They can be found in wine , jam , syrup , juice , soft spreads , tea , salsa , chili starters , extracts , beer , ice cream , gummies and tinctures . The name `` chokeberry '' comes from the astringency of the fruits , which create a sensation making one 's mouth pucker . Chokeberries are often mistakenly called chokecherries , which is the common name for Prunus virginiana . Further adding to the ambiguity , a variety of Prunus virginiana is named melanocarpa , readily confused with black chokeberry , commonly referred to as `` black chokeberry '' or `` aronia '' . Aronia berries and chokecherries are both high in polyphenolic compounds , such as anthocyanins , yet the two plants are distantly related within the Rosaceae family |
Arctic | The Arctic ( -LSB- ˈɑrktɪk -RSB- or -LSB- ˈɑrtɪk -RSB- ) is a polar region located at the northernmost part of Earth . The Arctic consists of the Arctic Ocean , adjacent seas , and parts of Alaska ( United States ) , Canada , Finland , Greenland ( Denmark ) , Iceland , Norway , Russia and Sweden . Land within the Arctic region has seasonally varying snow and ice cover , with predominantly treeless permafrost-containing tundra . Arctic seas contain seasonal sea ice in many places . The Arctic region is a unique area among Earth 's ecosystems . For example , the cultures in the region and the Arctic indigenous peoples have adapted to its cold and extreme conditions . In recent years , Arctic sea ice decline has been caused by global warming . Life in the Arctic includes organisms living in the ice , zooplankton and phytoplankton , fish and marine mammals , birds , land animals , plants and human societies . Arctic land is bordered by the subarctic . |
Arctic_Satellite_Composite_Project | The Arctic Satellite Composite Project , a grant funded by the Arctic Sciences division of the National Science Foundation ( NSF ) , is a project dedicated to developing satellite composite images , of various wavelengths , over the Arctic polar region of the globe . The project , based out of the Space Science and Engineering Center ( SSEC ) at the University of Wisconsin , is headed by Principal Investigator ( PI ) Dr. Matthew Lazzara , with assistance from co-PI Shelley Knuth . Since the project 's inception in 2007 , composite images in the infrared , water vapor , short-wave , and long-wave wavelengths have been generated over the region . The images are produced every three hours , on the synoptic hour . To generate the composite images , swaths of satellite images from geo-stationary and polar-orbiting satellites are collected within + / - 50 minutes of the top of the hour , and `` spliced '' together to form one image of the entire region . The images are centered at the North Pole , and extend as far south as 45 ° . The images have a resolution of 5 km . The Arctic satellite composites have already been used in their earliest form to support studies of Arctic pollution . They have been used operationally to support the polar study using aircraft , remote sensing , surface measurements and models of climate , chemistry , aerosols and transport ( POLARCAT ) , and Arctic research of the composition of the troposphere from aircraft and satellites ( ARCTAS ) campaigns during the International Polar Year . Future work on the generation of the satellite composite imagery will include visible composite generation as well as hourly composite generation . It is anticipated this work will be completed in 2010 . |
Antarctic_continental_shelf | The Antarctic continental shelf is a geological feature that underlies the Southern Ocean , surrounding the continent of Antarctica . The shelf is generally narrow and unusually deep , its edge lying at depths averaging 500 meters ( the global mean is around 100 meters ) , with troughs extending as far as 2000 meters deep . It is home to a thriving ecosystem of penguins and cold-water fish and crustaceans . Several countries have issued proclamations claiming ownership over parts of the shelf , including Chile ( since 1947 ) , Australia ( since 1953 ) , France , and Argentina . |
Antarctic_Treaty_System | The Antarctic Treaty and related agreements , collectively known as the Antarctic Treaty System ( ATS ) , regulate international relations with respect to Antarctica , Earth 's only continent without a native human population . For the purposes of the treaty system , Antarctica is defined as all of the land and ice shelves south of 60 ° S latitude . The treaty , entering into force in 1961 and having 53 parties as of 2016 , sets aside Antarctica as a scientific preserve , establishes freedom of scientific investigation and bans military activity on that continent . The treaty was the first arms control agreement established during the Cold War . The Antarctic Treaty Secretariat headquarters have been located in Buenos Aires , Argentina , since September 2004 . The main treaty was opened for signature on December 1 , 1959 , and officially entered into force on June 23 , 1961 . The original signatories were the 12 countries active in Antarctica during the International Geophysical Year ( IGY ) of 1957 -- 58 . The twelve countries that had significant interests in Antarctica at the time were : Argentina , Australia , Belgium , Chile , France , Japan , New Zealand , Norway , South Africa , the Soviet Union , the United Kingdom and the United States . These countries had established over 50 Antarctic stations for the IGY . The treaty was a diplomatic expression of the operational and scientific cooperation that had been achieved `` on the ice '' . |
Apollo_17 | Apollo 17 was the final mission of NASA 's Apollo program , the enterprise that landed the first humans on the Moon . Launched at 12:33 a.m. Eastern Standard Time ( EST ) on December 7 , 1972 , with a crew made up of Commander Eugene Cernan , Command Module Pilot Ronald Evans , and Lunar Module Pilot Harrison Schmitt , it was the last use of Apollo hardware for its original purpose ; after Apollo 17 , extra Apollo spacecraft were used in the Skylab and Apollo -- Soyuz programs . Apollo 17 was the first night launch of a U.S. human spaceflight and the final manned launch of a Saturn V rocket . It was a `` J-type mission '' which included three days on the lunar surface , extended scientific capability , and the third Lunar Roving Vehicle ( LRV ) . While Evans remained in lunar orbit in the Command/Service Module ( CSM ) , Cernan and Schmitt spent just over three days on the moon in the Taurus -- Littrow valley and completed three moonwalks , taking lunar samples and deploying scientific instruments . Evans took scientific measurements and photographs from orbit using a Scientific Instruments Module mounted in the Service Module . The landing site was chosen with the primary objectives of Apollo 17 in mind : to sample lunar highland material older than the impact that formed Mare Imbrium , and investigate the possibility of relatively new volcanic activity in the same area . Cernan , Evans and Schmitt returned to Earth on December 19 after a 12-day mission . Apollo 17 is the most recent manned Moon landing and was the last time humans travelled beyond low Earth orbit . It was also the first mission to be commanded by a person with no background as a test pilot , and the first to have no one on board who had been a test pilot ; X-15 test pilot Joe Engle lost the lunar module pilot assignment to Schmitt , a scientist . The mission broke several records : the longest moon landing , longest total extravehicular activities ( moonwalks ) , largest lunar sample , and longest time in lunar orbit . |
Anoxic_event | Oceanic anoxic events or anoxic events ( anoxia conditions ) refer to intervals in the Earth 's past where portions of oceans become depleted in oxygen ( O2 ) at depths over a large geographic area . During some of these events , euxinia , waters that contained hydrogen sulfide , developed . Although anoxic events have not happened for millions of years , the geological record shows that they happened many times in the past . Anoxic events coincided with several mass extinctions and may have contributed to them . These mass extinctions include some that geobiologists use as time markers in biostratigraphic dating . Many geologists believe oceanic anoxic events are strongly linked to slowing of ocean circulation , climatic warming , and elevated levels of greenhouse gases . Researchers have proposed enhanced volcanism ( the release of CO2 ) as the `` central external trigger for euxinia '' . |
Arctic_Circle_(disambiguation) | Arctic Circle is one of the five major circles of latitude that mark maps of the Earth . It may also refer to : Arctic Circle Restaurants , a chain of burger and shake restaurants based in Midvale , Utah , USA Arctic Circle Air , an American airline based in Fairbanks , Alaska , USA Arctic Circle Raceway , the biggest race track in Norway Arctic circle theorem in mathematics Arctic Circle ( organization ) , an annual interdisciplinary conference related to Arctic issues based in Reykjavík , Iceland Arctic Circle Trail , a trekking tour in West Greenland The Arctic Circle , the first track off of the 2006 album He Poos Clouds by Owen Pallett In the astronomy of the ancient Greeks , the `` Arctic Circle '' was an observer-dependent circle on the celestial sphere , centred on the northern celestial pole and tangential to the horizon , within which all the northern circumpolar stars lie . |
Anticyclone | An anticyclone ( that is , opposite to a cyclone ) is a weather phenomenon defined by the United States National Weather Service 's glossary as `` a large-scale circulation of winds around a central region of high atmospheric pressure , clockwise in the Northern Hemisphere , counterclockwise in the Southern Hemisphere '' . Effects of surface-based anticyclones include clearing skies as well as cooler , drier air . Fog can also form overnight within a region of higher pressure . Mid-tropospheric systems , such as the subtropical ridge , deflect tropical cyclones around their periphery and cause a temperature inversion inhibiting free convection near their center , building up surface-based haze under their base . Anticyclones aloft can form within warm core lows such as tropical cyclones , due to descending cool air from the backside of upper troughs such as polar highs , or from large scale sinking such as the subtropical ridge . |
Architecture_of_New_York_City | The building form most closely associated with New York City is the skyscraper , which has shifted many commercial and residential districts from low-rise to high-rise . Surrounded mostly by water , the city has amassed one of the largest and most varied collection of skyscrapers in the world . New York has architecturally significant buildings in a wide range of styles spanning distinct historical and cultural periods . These include the Woolworth Building ( 1913 ) , an early Gothic revival skyscraper with large-scale gothic architectural detail . The 1916 Zoning Resolution required setback in new buildings , and restricted towers to a percentage of the lot size , to allow sunlight to reach the streets below . The Art Deco design of the Chrysler Building ( 1930 ) and Empire State Building ( 1931 ) , with their tapered tops and steel spires , reflected the zoning requirements . The Chrysler building is considered by many historians and architects to be one of New York 's finest , with its distinctive ornamentation such as V-shaped lighting inserts capped by a steel spire at the tower 's crown . An early influential example of the international style in the United States is the Seagram Building ( 1957 ) , distinctive for its facade using visible bronze-toned I-beams to evoke the building 's structure . The Condé Nast Building ( 2000 ) is an important example of green design in American skyscrapers . The character of New York 's large residential districts is often defined by the elegant brownstone rowhouses , townhouses , and tenements that were built during a period of rapid expansion from 1870 to 1930 . In contrast , New York City also has neighborhoods that are less densely populated and feature free-standing dwellings . In the outer boroughs , large single-family homes are common in various architectural styles such as Tudor Revival and Victorian . Split two-family homes are also widely available across the outer boroughs , especially in the Flushing area . Stone and brick became the city 's building materials of choice after the construction of wood-frame houses was limited in the aftermath of the Great Fire of 1835 . Unlike Paris , which for centuries was built from its own limestone bedrock , New York has always drawn its building stone from a far-flung network of quarries and its stone buildings have a variety of textures and hues . A distinctive feature of many of the city 's buildings is the presence of wooden roof-mounted water towers . In the 19th century , the city required their installation on buildings higher than six stories to prevent the need for excessively high water pressures at lower elevations , which could burst municipal water pipes . Garden apartments became popular during the 1920s in outlying areas , including Jackson Heights in Queens , which became more accessible with expansion of the subway . __ TOC __ |
Anthropocene | The Anthropocene is a proposed epoch dating from the commencement of significant human impact on the Earth 's geology and ecosystems . The Anthropocene thus includes , but also transcends , the duration of anthropogenic climate change . , neither the International Commission on Stratigraphy nor the International Union of Geological Sciences has yet officially approved the term as a recognized subdivision of geological time , although the Working Group on the Anthropocene ( WGA ) voted to formally designate the epoch Anthropocene and presented the recommendation to the International Geological Congress on 29 August 2016 . |
Anaheim,_California | Anaheim ( pronounced -LSB- ˈænəhaɪm -RSB- ) is a city in Orange County , California , part of the Los Angeles metropolitan area . As of the 2010 United States Census , the city had a population of 336,265 , making it the most populous city in Orange County and the 10th most populous city in California . Anaheim is the second largest city in Orange County in terms of land area ( after Irvine ) and is known for its theme parks , the Anaheim Convention Center , and its two major sports teams : the Anaheim Ducks ice hockey club and the Angels baseball team . Anaheim was founded by fifty German families in 1857 and incorporated as the second city in Los Angeles County on March 18 , 1876 ; Orange County would later be split off from Los Angeles County in 1889 . Anaheim remained largely a rural community until Disneyland opened in the city in 1955 . This led to the construction of several hotels and motels around the area , and residential districts in Anaheim soon followed . The city also developed into an industrial center , producing electronics , aircraft parts and canned fruit . Anaheim 's city limits extend from Cypress in the west to the Riverside County line in the east and encompass a diverse collection of neighborhoods and communities . Anaheim Hills is a master-planned community located in the city 's eastern stretches that is home to many of the city 's affluent . Downtown Anaheim has three mixed-use historic districts , the largest of which is the Anaheim Colony . The Anaheim Resort , a commercial district , includes Disneyland , Disney California Adventure , and numerous hotels and retail complexes . The Platinum Triangle , a neo-urban redevelopment district surrounding Angel Stadium , is planned to be populated with mixed-use streets and high-rises . Anaheim Canyon is an industrial district north of California State Route 91 and east of California State Route 57 . |
Antofagasta | Antofagasta ( -LSB- antofaˈɣasta -RSB- ) is a port city in northern Chile , about 1100 km north of Santiago . It is the capital of Antofagasta Province and Antofagasta Region . According to the 2012 census , the city has a population of 345,420 . Formerly part of Bolivia , Antofagasta was captured by Chile in the War of the Pacific ( 1879 -- 83 ) , and the transfer of sovereignty was finalized in the 1904 Treaty of Peace and Friendship between the two countries . The city of Antofagasta is closely linked to mining activity , being a major mining area of the country . The last decade has been a steady growth in the areas of construction , retail , hotel accommodations , population growth , and remarkable skyline development . Antofagasta has the highest GDP per capita of Chile , 37,000 USD and the 3rd place for Human Development Index just after Metropolitana de Santiago Region and Magallanes and Antártica Chilena Region . |
Appalachian_Mountains | The Appalachian Mountains ( -LSB- æpəˈlæʃᵻn , _ - ˈleɪtʃᵻn -RSB- , There are at least eight possible pronunciations depending on three factors : Whether the stressed vowel is -LSB- slinkeɪ -RSB- or -LSB- slinkæ -RSB- , Whether the `` ch '' is pronounced as a fricative -LSB- slinkʃ -RSB- or an affricate -LSB- slinktʃ -RSB- , and Whether the final - ia is the monophthong -LSB- slinkᵻ -RSB- or the vowel sequence -LSB- iə -RSB- . les Appalaches ) , often called the Appalachians , are a system of mountains in eastern North America . The Appalachians first formed roughly 480 million years ago during the Ordovician Period . It once reached elevations similar to those of the Alps and the Rocky Mountains before naturally occurring erosion . The Appalachian chain is a barrier to east-west travel , as it forms a series of alternating ridgelines and valleys oriented in opposition to most roads running east or west . Definitions vary on the precise boundaries of the Appalachians . The United States Geological Survey ( USGS ) defines the Appalachian Highlands physiographic division as consisting of thirteen provinces : the Atlantic Coast Uplands , Eastern Newfoundland Atlantic , Maritime Acadian Highlands , Maritime Plain , Notre Dame and Mégantic Mountains , Western Newfoundland Mountains , Piedmont , Blue Ridge , Valley and Ridge , Saint Lawrence Valley , Appalachian Plateaus , New England province , and the Adirondack provinces . < ref name = `` USGS-Water '' > </ref> A common variant definition does not include the Adirondack Mountains , which geologically belong to the Grenville Orogeny and have a different geological history from the rest of the Appalachians . < ref name = geomorph > </ref> < ref name = peakbag > </ref> < ref name = weidensaul > </ref> |
Argument_from_nonbelief | An argument from nonbelief is a philosophical argument that asserts an inconsistency between the existence of God and a world in which people fail to recognize him . It is similar to the classic argument from evil in affirming an inconsistency between the world that exists and the world that would exist if God had certain desires combined with the power to see them through . There are two key varieties of the argument . The argument from reasonable nonbelief ( or the argument from divine hiddenness ) was first elaborated in J. L. Schellenberg 's 1993 book Divine Hiddenness and Human Reason . This argument says that if God existed ( and was perfectly good and loving ) every reasonable person would have been brought to believe in God ; however , there are reasonable nonbelievers ; therefore , this God does not exist . Theodore Drange subsequently developed the argument from nonbelief , based on the mere existence of nonbelief in God . Drange considers the distinction between reasonable ( by which Schellenberg means inculpable ) and unreasonable ( culpable ) nonbelief to be irrelevant and confusing . Nevertheless , the overwhelming majority of academic discussion is concerned with Schellenberg 's formulation . |
Anoxic_waters | Anoxic waters are areas of sea water , fresh water , or groundwater that are depleted of dissolved oxygen and are a more severe condition of hypoxia . The US Geological Survey defines anoxic groundwater as those with dissolved oxygen concentration of less than 0.5 milligrams per litre . This condition is generally found in areas that have restricted water exchange . In most cases , oxygen is prevented from reaching the deeper levels by a physical barrier as well as by a pronounced density stratification , in which , for instance , heavier hypersaline waters rest at the bottom of a basin . Anoxic conditions will occur if the rate of oxidation of organic matter by bacteria is greater than the supply of dissolved oxygen . Anoxic waters are a natural phenomenon , and have occurred throughout geological history . In fact , some postulate that the Permian -- Triassic extinction event , a mass extinction of species from world 's oceans , resulted from widespread anoxic conditions . At present anoxic basins exist , for example , in the Baltic Sea , and elsewhere ( see below ) . Recently , there have been some indications that eutrophication has increased the extent of the anoxic zones in areas including the Baltic Sea , the Gulf of Mexico , and Hood Canal in Washington State . |
Archaea | The Archaea ( -LSB- ɑrˈkiːə -RSB- or -LSB- ɑrˈkeɪə -RSB- or ) constitute a domain and kingdom of single-celled microorganisms . These microbes ( archaea ; singular archaeon ) are prokaryotes , meaning that they have no cell nucleus or any other membrane-bound organelles in their cells . Archaea were initially classified as bacteria , receiving the name archaebacteria ( in the Archaebacteria kingdom ) , but this classification is outdated . Archaeal cells have unique properties separating them from the other two domains of life , Bacteria and Eukaryota . The Archaea are further divided into multiple recognized phyla . Classification is difficult because the majority have not been isolated in the laboratory and have only been detected by analysis of their nucleic acids in samples from their environment . Archaea and bacteria are generally similar in size and shape , although a few archaea have very strange shapes , such as the flat and square-shaped cells of Haloquadratum walsbyi . Despite this morphological similarity to bacteria , archaea possess genes and several metabolic pathways that are more closely related to those of eukaryotes , notably the enzymes involved in transcription and translation . Other aspects of archaeal biochemistry are unique , such as their reliance on ether lipids in their cell membranes , including archaeols . Archaea use more energy sources than eukaryotes : these range from organic compounds , such as sugars , to ammonia , metal ions or even hydrogen gas . Salt-tolerant archaea ( the Haloarchaea ) use sunlight as an energy source , and other species of archaea fix carbon ; however , unlike plants and cyanobacteria , no known species of archaea does both . Archaea reproduce asexually by binary fission , fragmentation , or budding ; unlike bacteria and eukaryotes , no known species forms spores . Archaea were initially viewed as extremophiles living in harsh environments , such as hot springs and salt lakes , but they have since been found in a broad range of habitats , including soils , oceans , and marshlands . They are also found in the human colon , oral cavity , and skin . Archaea are particularly numerous in the oceans , and the archaea in plankton may be one of the most abundant groups of organisms on the planet . Archaea are a major part of Earth 's life and may play roles in both the carbon cycle and the nitrogen cycle . No clear examples of archaeal pathogens or parasites are known , but they are often mutualists or commensals . One example is the methanogens that inhabit human and ruminant guts , where their vast numbers aid digestion . Methanogens are also used in biogas production and sewage treatment , and biotechnology exploits enzymes from extremophile archaea that can endure high temperatures and organic solvents . |
Aragonite | Aragonite is a carbonate mineral , one of the two most common , naturally occurring , crystal forms of calcium carbonate , CaCO3 ( the other forms being the minerals calcite and vaterite ) . It is formed by biological and physical processes , including precipitation from marine and freshwater environments . Aragonite 's crystal lattice differs from that of calcite , resulting in a different crystal shape , an orthorhombic crystal system with acicular crystal . Repeated twinning results in pseudo-hexagonal forms . Aragonite may be columnar or fibrous , occasionally in branching stalactitic forms called flos-ferri ( `` flowers of iron '' ) from their association with the ores at the Carinthian iron mines . |
Arctic_Circle | The Arctic Circle is the most northerly of the abstract five major circles of latitude as shown on maps of the Earth . It marks the northernmost point at which the noon sun is just visible on the northern winter solstice and the southernmost point at which the midnight sun is just visible on the northern summer solstice . The region north of this circle is known as the Arctic , and the zone just to the south is called the Northern Temperate Zone . North of the Arctic Circle , the sun is above the horizon for twenty-four continuous hours at least once per year ( and therefore visible at midnight ) and below the horizon for twenty-four continuous hours at least once per year ( and therefore not visible at noon ) ; this is also true within the equivalent polar circle in the Southern Hemisphere , the Antarctic Circle . The position of the Arctic Circle is not fixed ; as of , it runs north of the Equator . Its latitude depends on the Earth 's axial tilt , which fluctuates within a margin of 2 ° over a 40,000-year period , due to tidal forces resulting from the orbit of the Moon . Consequently , the Arctic Circle is currently drifting northwards at a speed of about 15 m per year . |
Antidisestablishmentarianism_(word) | The English word antidisestablishmentarianism ( -LSB- æn.taiˌdɪs.ɛsˌtæb.lɪʃ.məntˈɛ.ri.ənˌɪ.zəm -RSB- ) is notable for its unusual length of 28 letters and 12 syllables , and is one of the longest words in the English language . It has been cited as the longest word in the English language , excluding coined and technical terms . The longest word found in a major dictionary is `` pneumonoultramicroscopicsilicovolcanoconiosis '' , but this is a technical term that was coined specifically to be the longest word . The word became known in the public realm in the United States via a popular television show in the 1950s , The $ 64,000 Question , when a young contestant correctly spelled it to win . A slightly longer , but less commonly accepted , variant of the word can be found in the Duke Ellington song `` You 're Just an Old Antidisestablishmentarianismist ; '' although , the correct construction of the word used in the song should be `` antidisestablishmentarianist '' ( without the `` ism '' ) , or `` antidisestablishmentarian . '' The word is also used by Eminem in his song `` Almost Famous '' . |
Antarctic | The Antarctic ( US English -LSB- æntˈɑrktɪk -RSB- , UK English -LSB- ænˈtɑrktɪk -RSB- or -LSB- æntˈɑrtɪk -RSB- and -LSB- ænˈtɑrtɪk -RSB- or -LSB- ænˈɑrtɪk -RSB- ) is a polar region , specifically the region around the Earth 's South Pole , opposite the Arctic region around the North Pole . The Antarctic comprises in the strict sense the continent of Antarctica and the island territories located on the Antarctic Plate . In a broader sense the Antarctic region include the ice shelves , waters , and island territories in the Southern Ocean situated south of the Antarctic Convergence , a zone approximately 32 to wide varying in latitude seasonally . The region covers some 20 % of the Southern Hemisphere , of which 5.5 % ( 14 million km2 ) is the surface area of the Antarctic continent itself . All of the land and ice shelves south of 60 ° S latitude are administrated under the Antarctic Treaty System . In a biogeographic sense , the Antarctic ecozone is one of eight ecozones of the Earth 's land surface . |
Artemis_(satellite) | Artemis is a geostationary earth orbit satellite ( GEOS ) for telecommunications , built by Alenia Spazio for ESA . The Artemis satellite operates at the 21.5 E orbital position . The mission was planned for many years , with launch initially intended for 1995 and slipping ; it was intended for launch on Ariane 5 but at one point there were suggestions that a Japanese H-II rocket might be used . Launched by an Ariane 5 rocket on 12 July 2001 , it originally reached an orbit much lower than planned ( 590 km x 17487 km ) due to a malfunction in the launch vehicle 's upper stage . It was remotely reconfigured to reach its intended station by means of a novel procedure . First , over the course of about a week , most of its chemical fuel was used to put it in a 31,000 km circular orbit ( by raising first the apogee then the perigee , going via a 590 km x 31000 km orbit ) . Then , its electric-ion motor -- originally intended for station keeping and for firing a few minutes at a time -- was instead kept running for most of 18 months , pushing the spacecraft into an outward spiral trajectory . It gained altitude at the rate of about 15 km per day , until it reached the intended geostationary orbit . On January 1 , 2014 Avanti , a London-based company , took the ownership of the satellite . |
Arctic_char | Arctic char or Arctic charr ( Salvelinus alpinus ) is a cold-water fish in the family Salmonidae , native to alpine lakes and arctic and subarctic coastal waters . Its distribution is circumpolar . It spawns in fresh water and populations can be lacustrine , riverine or anadromous , where they return from the ocean to their fresh water birth rivers to spawn . No other freshwater fish is found as far north ; it is , for instance , the only fish species in Lake Hazen on Ellesmere Island in the Canadian Arctic . It is one of the rarest fish species in Britain , found mainly in deep , cold , glacial lakes , and is at risk from acidification . In other parts of its range , such as the Nordic countries , it is much more common , and is fished extensively . In Siberia , it is known as golets and it has been introduced in lakes where it sometimes threatens less hardy endemic species , such as the small-mouth char and the long-finned char in Elgygytgyn Lake . The Arctic char is closely related to both salmon and lake trout , and has many characteristics of both . The fish is highly variable in colour , depending on the time of year and the environmental conditions of the lake where it lives . Individual fish can weigh 20 lb or more with record-sized fish having been taken by anglers in northern Canada , where it is known as iqaluk or tariungmiutaq in Inuktitut . Generally , whole market-sized fish are between 2 and . The flesh colour can range from a bright red to a pale pink . |
Arctic_sea_ice_decline | Arctic sea ice decline is the sea ice loss observed in recent decades in the Arctic Ocean . The Intergovernmental Panel on Climate Change ( IPCC ) Fourth Assessment Report states that greenhouse gas forcing is largely , but not wholly , responsible for the decline in Arctic sea ice extent . A study from 2011 suggested that internal variability enhanced the greenhouse gas forced sea ice decline over the last decades . A study from 2007 found the decline to be `` faster than forecasted '' by model simulations . The IPCC Fifth Assessment Report concluded with high confidence that sea ice continues to decrease in extent , and that there is robust evidence for the downward trend in Arctic summer sea ice extent since 1979 . It has been established that the region is at its warmest for at least 40,000 years and the Arctic-wide melt season has lengthened at a rate of 5 days per decade ( from 1979 to 2013 ) , dominated by a later autumn freezeup . Sea ice changes have been identified as a mechanism for polar amplification . |
Arctic_ice_pack | The Arctic ice pack is the ice cover of the Arctic Ocean and its vicinity . The Arctic ice pack undergoes a regular seasonal cycle in which ice melts in spring and summer , reaches a minimum around mid-September , then increases during fall and winter . Summer ice cover in the Arctic is about 50 % of winter cover . Some of the ice survives from one year to the next . Currently 28 % of Arctic basin sea ice is multi-year ice , thicker than seasonal ice : up to 3 - thick over large areas , with ridges up to 20 m thick . As well as the regular seasonal cycle there has been an underlying trend of declining sea ice in the Arctic in recent decades . |
Antarctic_Circumpolar_Current | The Antarctic Circumpolar Current ( ACC ) is an ocean current that flows clockwise from west to east around Antarctica . An alternative name for the ACC is the West Wind Drift . The ACC is the dominant circulation feature of the Southern Ocean and has a mean transport of 100-150 Sverdrups ( Sv , million m ³ / s ) , making it the largest ocean current . More recent research even puts this number at over 173 Sv . The current is circumpolar due to the lack of any landmass connecting with Antarctica and this keeps warm ocean waters away from Antarctica , enabling that continent to maintain its huge ice sheet . Associated with the Circumpolar Current is the Antarctic Convergence , where the cold Antarctic waters meet the warmer waters of the subantarctic , creating a zone of upwelling nutrients . These nurture high levels of phytoplankton with associated copepods and krill , and resultant foodchains supporting fish , whales , seals , penguins , albatrosses and a wealth of other species . The ACC has been known to sailors for centuries ; it greatly speeds up any travel from west to east , but makes sailing extremely difficult from east to west ; though this is mostly due to the prevailing westerly winds . The circumstances preceding the mutiny on the Bounty and Jack London 's story `` Make Westing '' poignantly illustrated the difficulty it caused for mariners seeking to round Cape Horn on the clipper ship route between New York and California . The clipper route , which is the fastest sailing route around the world , follows the ACC around three continental capes -- Cape Agulhas ( Africa ) , South East Cape ( Australia ) and Cape Horn ( South America ) . The current creates the Ross and Weddell gyres . |
Anacortes,_Washington | Anacortes -LSB- ˌænəˈkɔrtəs -RSB- is a city in Skagit County , Washington , United States . The name `` Anacortes '' is an adaptation of the name of Anne Curtis Bowman , who was the wife of early Fidalgo Island settler Amos Bowman . Anacortes ' population was 15,778 at the time of the 2010 census . It is one of two principal cities of and included in the Mount Vernon-Anacortes Metropolitan Statistical Area . Anacortes is known for the Washington State Ferries dock and terminal serving Lopez Island , Shaw Island , Orcas Island , and San Juan Island , as well as Victoria , British Columbia ( via Sidney , British Columbia ) on Vancouver Island . There is also a Skagit County-operated ferry that serves Guemes Island , a residential island located across Guemes Channel , north of Anacortes . |
Arabian_Peninsula | The Arabian Peninsula , simplified Arabia ( الجزيرة العربية , `` Arabian island '' ) is a peninsula of Western Asia situated northeast of Africa on the Arabian plate . From a geological perspective , it is considered a subcontinent of Asia . It is the largest peninsula in the world , at 3237500 sqkm . The Arabian Peninsula consists of the countries Yemen , Oman , Qatar , Bahrain , Kuwait , Saudi Arabia and the United Arab Emirates , and parts of Jordan and Iraq . The peninsula formed as a result of the rifting of the Red Sea between 56 and 23 million years ago , and is bordered by the Red Sea to the west and southwest , the Persian Gulf to the northeast , the Levant to the north and the Indian Ocean to the southeast . The Arabian Peninsula plays a critical geopolitical role in the Middle East and the Arab world due to its vast reserves of oil and natural gas . Before the modern era , it was divided into four distinct regions : Hejaz , Najd , Southern Arabia ( Hadhramaut ) and Eastern Arabia . Hejaz and Najd make up most of Saudi Arabia . Southern Arabia consists of Yemen and some parts of Saudi Arabia ( Najran , Jizan , Asir ) and Oman ( Dhofar ) . Eastern Arabia consists of the entire coastal strip of the Persian Gulf . |
Arctostaphylos | Arctostaphylos ( -LSB- ˌɑːrktoʊˈstæfᵻləs , _ - lɒs -RSB- arkto bear + staphyle grape ) is a genus of plants comprising the manzanitas ( -LSB- ˌmænzəˈniːtəz -RSB- ) and bearberries . They are shrubs or small trees . There are about 60 species of Arctostaphylos , ranging from ground-hugging arctic , coastal , and mountain species to small trees up to 6 m tall . Most are evergreen ( one species deciduous ) , with small oval leaves 1 -- 7 cm long , arranged spirally on the stems . The flowers are bell-shaped , white or pale pink , and borne in small clusters of 2-20 together ; flowering is in the spring . The fruit are small berries , ripening in the summer or autumn . The berries of some species are edible . Arctostaphylos species are used as food plants by the larvae of some Lepidoptera species including Coleophora arctostaphyli ( which feeds exclusively on A. uva-ursi ) and Coleophora glaucella . |
Anthropogenic_biome | Anthropogenic biomes , also known as anthromes or human biomes , describe the terrestrial biosphere in its contemporary , human-altered form using global ecosystem units defined by global patterns of sustained direct human interaction with ecosystems . Anthromes were first named and mapped by Erle Ellis and Navin Ramankutty in their 2008 paper , `` Putting People in the Map : Anthropogenic Biomes of the World '' . Anthrome maps now appear in numerous textbooks and in the National Geographic World Atlas |
Antimatter | In particle physics , antimatter is a material composed of the antiparticle `` partners '' to the corresponding particles of ordinary matter . A particle and its antiparticle have the same mass as one another , but opposite electric charge and other quantum numbers . For example , a proton has positive charge while an antiproton has negative charge . A collision between any particle and its antiparticle partner leads to their mutual annihilation , giving rise to various proportions of intense photons ( gamma rays ) , neutrinos , and sometimes less-massive particle -- antiparticle pairs . The consequence of annihilation is a release of energy available for heat or work , proportional to the total matter and antimatter mass , in accord with the mass -- energy equivalence equation , . Formally , antimatter particles can be defined by their negative baryon number or lepton number , while `` normal '' ( non-antimatter ) matter particles have a positive baryon or lepton number . These two classes of particles are the antiparticle partners of one another . Antimatter particles bind with one other to form antimatter , just as ordinary particles bind to form normal matter . For example , a positron ( the antiparticle of the electron ) and an antiproton ( the antiparticle of the proton ) can form an antihydrogen atom . Physical principles indicate that complex antimatter atomic nuclei are possible , as well as anti-atoms corresponding to the known chemical elements . There is considerable speculation as to why the observable universe is composed almost entirely of ordinary matter , as opposed to an even mixture of matter and antimatter . This asymmetry of matter and antimatter in the visible universe is one of the great unsolved problems in physics . The process by which this inequality between matter antimatter particles developed is called baryogenesis . Antimatter in the form of anti-atoms is one of the most difficult materials to produce . Individual antimatter particles , however , are commonly produced by particle accelerators and in some types of radioactive decay . The nuclei of antihelium have been artificially produced with difficulty . These are the most complex anti-nuclei so far observed . |
Arctic_Lowlands | The Arctic Lowlands and Hudson Bay Lowlands are a physiographic division , lying between the Canadian Shield and the Innuitian region To the south of the surfaces and lowland plains . This is a region of tundra , a treeless Plain , with a cold , dry climate and poorly drained soil . Most of the Arctic Lowlands region is located in Nunavut . The Arctic Lowlands are plains located in Canada . Plains are extensive areas of level or gently rolling land . In North America there is a large , flat interior Plain . They are also part of what is commonly referred to as the Arctic Archipelago , occupying much of the central Canadian Arctic . They are made up of a series of islands located in Canada 's far north , and havd remains frozen most of the year . However , the Paleozoic sedimentary rock , from which the Lowlands are formed , contains lignite ( a form of coal ) , oil , and natural gas deposits . Limestone is very abundant as well . The Arctic Lowlands have a small human population . The terrain is mostly ice , snow , rock , and it is full of marshes , especially in the winter . Animals that live in the area include polar bears , char , Arctic hares and Arctic foxes . This region is being affected by global warming . It is very cold and human life may be difficult . Many suffer from lack of food in this region . Commonly known as the Hudson Bay-Arctic Lowlands , the Hudson Bay part is over 50 % water . |
Antarctic_realm | Antarctica is one of eight terrestrial biogeographic realms . The ecosystem includes Antarctica and several island groups in the southern Atlantic and Indian Oceans . The continent of Antarctica is so cold and dry that it has supported only 2 vascular plants for millions of years , and its flora presently consists of around 250 lichens , 100 mosses , 25-30 liverworts , and around 700 terrestrial and aquatic algal species , which live on the areas of exposed rock and soil around the shore of the continent . Antarctica 's two flowering plant species , the Antarctic hair grass ( Deschampsia antarctica ) and Antarctic pearlwort ( Colobanthus quitensis ) , are found on the northern and western parts of the Antarctic Peninsula . Antarctica is also home to a diversity of animal life , including penguins , seals , and whales . Several Antarctic island groups are considered part of the Antarctica realm , including South Georgia and the South Sandwich Islands , South Orkney Islands , the South Shetland Islands , Bouvet Island , the Crozet Islands , Prince Edward Islands , Heard Island , the Kerguelen Islands , and the McDonald Islands . These islands have a somewhat milder climate than Antarctica proper , and support a greater diversity of tundra plants , although they are all too windy and cold to support trees . Antarctic krill is the keystone species of the ecosystem of the Southern Ocean , and is an important food organism for whales , seals , leopard seals , fur seals , crabeater seals , squid , icefish , penguins , albatrosses and many other birds . The ocean there is so full of phytoplankton because around the ice continent water rises from the depths to the light flooded surface , bringing nutrients from all oceans back to the photic zone . On August 20 , 2014 , scientists confirmed the existence of microorganisms living 800 m below the ice of Antarctica . |
Arctic_Ocean | The Arctic Ocean is the smallest and shallowest of the world 's five major oceans . The International Hydrographic Organization ( IHO ) recognizes it as an ocean , although some oceanographers call it the Arctic Mediterranean Sea or simply the Arctic Sea , classifying it a mediterranean sea or an estuary of the Atlantic Ocean . Alternatively , the Arctic Ocean can be seen as the northernmost part of the all-encompassing World Ocean . Located mostly in the Arctic north polar region in the middle of the Northern Hemisphere , the Arctic Ocean is almost completely surrounded by Eurasia and North America . It is partly covered by sea ice throughout the year and almost completely in winter . The Arctic Ocean 's surface temperature and salinity vary seasonally as the ice cover melts and freezes ; its salinity is the lowest on average of the five major oceans , due to low evaporation , heavy fresh water inflow from rivers and streams , and limited connection and outflow to surrounding oceanic waters with higher salinities . The summer shrinking of the ice has been quoted at 50 % . The US National Snow and Ice Data Center ( NSIDC ) uses satellite data to provide a daily record of Arctic sea ice cover and the rate of melting compared to an average period and specific past years . |
Annual_cycle_of_sea_level_height | The annual cycle of sea level height ( or seasonal cycle or annual harmonic ) describes the variation of sea level that occurs with a period of one year . Historically , analysis of the annual cycle has been limited by locations with tide gauge records , i.e. , coastlines and some islands in the deep ocean , and by sparse records in the Southern Hemisphere . Since 1992 , satellite-based altimeters have provided near global coverage of sea level variability , allowing for a more thorough understanding of the annual cycle both in the deep ocean and in coastal margins . |
April_2010_Rio_de_Janeiro_floods_and_mudslides | The April 2010 Rio de Janeiro floods and mudslides was an extreme weather event that affected the State of Rio de Janeiro in Brazil in the first days of April 2010 . At least 212 people died , 161 people have been injured ( including several rescuers ) , while at least 15,000 people have been made homeless . A further 10,000 homes are thought to be at risk from mudslides , most of them in the favelas , the shanty towns built on the hillsides above downtowns . Damage from the flooding has been estimated at 23.76 billion reais ( US$ 13.3 bn , $ 9.9 bn ) , about 8 % of the gross domestic product ( GDP ) of Rio de Janeiro State . The flooding particularly affected the city of Rio de Janeiro , where at least 60 people died , and its surrounding area . Deaths were also been reported in the cities of Niterói ( 132 ) , São Gonçalo ( 16 ) , Paracambi ( 1 ) , Engenheiro Paulo de Frontin ( 1 ) , Magé ( 1 ) , Nilópolis ( 1 ) and Petrópolis ( 1 ) . Several municipalities , including Niterói and municipalities to the east such as Maricá and Araruama , have declared states of emergency or of public calamity . The Governor of Rio de Janeiro State , Sérgio Cabral , declared three days of official mourning for the dead . Heavy rain started at around 5 p.m. local time ( 2000 UTC ) on Monday 5 April in Rio de Janeiro city , and continued for 24 hours , with a total of 28.8 cm ( 11 1/2 in . ) of rain falling , more than was predicted for the whole of April and the heaviest rainfall for thirty years . The Brazilian TV station Globo said the rainfall was equivalent to 300,000 Olympic swimming pools of water . There were drivers who were forced to sleep in their cars . There were also firemen who used rubber dinghies to rescue passengers from stranded buses , and shopkeepers who worked very quickly to prevent the rainfall from destroying their businesses . Rio de Janeiro mayor Eduardo Paes admitted that the city 's preparedness for heavy rainfall had been `` less than zero , '' but added `` there is n't a city that would n't have had problems with this level of rainfall . '' A further landslide hit a slum in Niterói late on 7 April . It is thought to have killed at least 150 . Around 200 people were missing in the town as of 13 April . After nearly 300 landslides hit the area , the statue of Christ the Redeemer was cut off from traffic for the first time in history . More than 300 homes were bulldozed after the landslides , and it is estimated that close to 12,000 families will need to be relocated by 2012 due to the damage from the floods . |
Arctic_geoengineering | Temperatures in the Arctic region have tended to increase more rapidly than the global average . Projections of sea ice loss that are adjusted to take account of recent rapid Arctic shrinkage suggest that the Arctic will likely be free of summer sea ice sometime between 2059 and 2078 . Various climate engineering schemes have been suggested to reduce the chance of significant and irreversible effects such as Arctic methane release . Several climate engineering proposals have been made which are specific to the Arctic . They are usually hydrological in nature , and principally centre upon measures to prevent Arctic ice loss . In addition , other solar radiation management climate engineering techniques , such as stratospheric sulfate aerosols have been proposed . These would cool the Arctic by adjusting the albedo of the atmosphere . |
Andes | The Andes or Andean Mountains ( Cordillera de los Andes ) are the longest continental mountain range in the world . They are a continuous range of highlands along the western edge of South America . This range is about 7000 km long , about 200 to wide ( widest between 18 ° south and 20 ° south latitude ) , and of an average height of about 4000 m . The Andes extend from north to south through seven South American countries : Venezuela , Colombia , Ecuador , Peru , Bolivia , Argentina and Chile . Along their length , the Andes are split into several ranges , which are separated by intermediate depressions . The Andes are the location of several high plateaus -- some of which host major cities , such as Quito , Bogotá , Arequipa , Medellín , Sucre , Mérida and La Paz . The Altiplano plateau is the world 's second-highest after the Tibetan plateau . These ranges are in turn grouped into three major divisions based on climate : the Tropical Andes , the Dry Andes , and the Wet Andes . The Andes are the world 's highest mountain range outside of Asia . The highest mountain outside Asia , Mount Aconcagua , rises to an elevation of about 6961 m above sea level . The peak of Chimborazo in the Ecuadorean Andes is farther from the Earth 's center than any other location on the Earth 's surface , due to the equatorial bulge resulting from the Earth 's rotation . The world 's highest volcanoes are in the Andes , including Ojos del Salado on the Chile-Argentina border , which rises to 6,893 m. The Andes are also part of the American Cordillera , a chain of mountain ranges ( cordillera ) that consists of an almost continuous sequence of mountain ranges that form the western `` backbone '' of North America , Central America , South America and Antarctica . |
Anishinaabe | Anishinaabe ( or Anishinabe , plural : Anishinaabeg ) is the autonym for a group of culturally related indigenous peoples of Canada and the United States that include the Odawa , Ojibwe , Potawatomi , Oji-Cree , Mississaugas , and Algonquin peoples . The Anishinaabeg speak Anishinaabemowin , or Anishinaabe languages that belong to the Algonquian language family . They traditionally have lived in the Northeast Woodlands and Subarctic . The word Anishinaabeg translates to `` people from whence lowered . '' Another definition refers to `` the good humans , '' meaning those who are on the right road or path given to them by the Creator Gichi-Manidoo , or Great Spirit . The Ojibwe historian , linguist , and author Basil Johnston wrote that its literal translation is `` Beings Made Out of Nothing '' or `` Spontaneous Beings , '' since the Anishinaabeg were created by divine breath . Anishinaabe is often mistakenly considered a synonym of Ojibwe ; however , it refers to a much larger group of tribes . |
Anti-nuclear_movement_in_France | In the 1970s , an anti-nuclear movement in France , consisting of citizens ' groups and political action committees , emerged . Between 1975 and 1977 , some 175,000 people protested against nuclear power in ten demonstrations . In 1972 , the anti-nuclear weapons movement maintained a presence in the Pacific , largely in response to French nuclear testing there . Activists , including David McTaggart from Greenpeace , defied the French government by sailing small vessels into the test zone and interrupting the testing program . In Australia , scientists issued statements demanding an end to the tests ; unions refused to load French ships , service French planes , or carry French mail ; and consumers boycotted French products . In 1985 the Greenpeace ship Rainbow Warrior was bombed and sunk by the French DGSE in Auckland , New Zealand , as it prepared for another protest of nuclear testing in French military zones . One crew member , Fernando Pereira of Portugal , photographer , drowned on the sinking ship . In January 2004 , up to 15,000 anti-nuclear protesters marched in Paris against a new generation of nuclear reactors , the European Pressurised Reactor ( EPR ) . On March 17 , 2007 , simultaneous protests , organised by Sortir du nucléaire , were staged in 5 French towns to protest construction of EPR plants . After Japan 's 2011 Fukushima nuclear disaster , thousands staged anti-nuclear protests around France , demanding reactors be closed . Protesters ' demands were focused on getting France to shut its oldest nuclear power station at Fessenheim . Many people also protested at the Cattenom nuclear plant , France 's second most powerful . In November 2011 , thousands of anti-nuclear protesters delayed a train carrying radioactive waste from France to Germany . Many clashes and obstructions made the journey the slowest one since the annual shipments of radioactive waste began in 1995 . Also in November 2011 , a French court fined nuclear power company Électricité de France $ 1.5 m and jailed two senior employees for spying on Greenpeace , including hacking into Greenpeace 's computer systems . The sentence was overturned by an appeals court in February 2013 . In March 2014 , police arrested 57 Greenpeace protesters who used a truck to break through security barriers and enter the Fessenheim nuclear power plant in eastern France . The activists hung antinuclear banners , but France 's nuclear safety authority said that the plant 's security had not been compromised . President Hollande has promised to close Fessenheim by 2016 , but Greenpeace wants immediate closure . |
Armstrong_Power_Plant | Armstrong Power Station is a coal fired thermal power station with 356 MW in Washington Township , Armstrong County along the Allegheny River across from Mahoning Creek and Templeton , Pennsylvania , about 10 miles north of Kittanning , Pennsylvania , USA whose two units went in service in 1958/1959 . The chimney of Armstrong Power Station , which was built in 1982 is 308.15 metres high and cost $ 13 million . The power plant was closed on September 1 , 2012 by FirstEnergy Corp. which is headquartered in Akron , Ohio , along with six other plants in the tri-county grid to comply with federal Environmental Protection Agency ( EPA ) guidelines that set new Mercury and Air Toxics Standards ( MATS ) and other environmental and air quality requirements . The decision was made not to invest in some of the smaller plants considering it would be quite expensive to install a scrubber and other air pollution control upgrades to keep the plant in operation . Larger plants in Pennsylvania had several hundred million dollars invested in them so they can continue operation . The coal industry related regulations have affected many jobs in Armstrong County , PA such as coal truck drivers , railroad operators , and local machine shops that service equipment . The other five coal power plants that closed include : Bay Shore Plant , Units 2-4 in Oregon , Ohio ; Eastlake Power Plant in Eastlake , Ohio ; Ashtabula Plant in Ashtabula , Ohio ; Lake Shore Plant in Cleveland , Ohio ; and the R. Paul Smith Power Station in Williamsport , Maryland . The facility is owned by Allegheny Energy Supply . |
Arid | A region is arid when it is characterized by a severe lack of available water , to the extent of hindering or preventing the growth and development of plant and animal life . Environments subject to arid climates tend to lack vegetation and are called xeric or desertic . Most `` arid '' climates surround the equator ; these places include most of Africa and parts of South America , Central America and Australia . |
Antarctic_Cold_Reversal | The Antarctic Cold Reversal ( ACR ) was an important episode of cooling in the climate history of the Earth during the deglaciation at the close of the last ice age . It illustrates the complexity of the climate changes at the transition from the Pleistocene to the Holocene Epochs . The Last Glacial Maximum and sea-level minimum occurred c. 21,000 years before present ( BP ) . Antarctic ice cores show gradual warming beginning 3000 years later . At about 14,700 BP , there was a large pulse of meltwater , identified as Meltwater pulse 1A , probably from either the Antarctic ice sheet or the Laurentide ice sheet . Meltwater pulse 1A produced a marine transgression that raised global sea level about 20 meters in two to five centuries and is thought to have influenced the start of the Bølling / Allerød interstadial , the major break with glacial cold in the Northern Hemisphere . Meltwater pulse 1A was followed in Antarctica and the Southern Hemisphere by a renewed cooling , the Antarctic Cold Reversal , in c. 14,500 BP , which lasted for two millennia -- an instance of warming causing cooling . The ACR brought an average cooling of perhaps 3 ° C . The Younger Dryas cooling , in the Northern Hemisphere , began while the Antarctic Cold Reversal was still ongoing , and the ACR ended in the midst of the Younger Dryas . This pattern of climate decoupling between the Northern and Southern Hemispheres and of `` southern lead , northern lag '' would manifest in subsequent climate events . The cause or causes of this hemispheric decoupling , of the `` lead/lag '' pattern and of the specific mechanisms of the warming and cooling trends are still subjects of study and dispute among climate researchers . The specific dating and intensity of the Antarctic Cold Reversal are also under debate . The onset of the Antarctic Cold Reversal was followed , after about 800 years , by an Oceanic Cold Reversal in the Southern Ocean . |
Aquatic_mammal | Aquatic and semiaquatic mammals are a diverse group of mammals that dwell partly or entirely in bodies of water . They include the various marine mammals who dwell in oceans , as well as various freshwater species , such as the European otter . They are not a taxon and are not unified by any distinct biological grouping , but rather their dependence on and integral relation to aquatic ecosystems . The level of dependence on aquatic life are vastly different among species , with the Amazonian manatee and river dolphins being completely aquatic and fully dependent on aquatic ecosystems ; whereas the Baikal seal feeds underwater but rests , molts , and breeds on land ; and the capybara and hippopotamus are able to venture in and out of water in search of food . Mammal adaptation to an aquatic lifestyle vary considerably between species . River dolphins and manatees are both fully aquatic and therefore are completely tethered to a life in the water . Seals are semiaquatic ; they spend the majority of their time in the water , but need to return to land for important activities such as mating , breeding and molting . In contrast , many other aquatic mammals , such as rhinoceroses , capybara , and water shrews , are much less adapted to aquatic living . Likewise , their diet ranges considerably as well , anywhere from aquatic plants and leaves to small fish and crustaceans . They play major roles in maintaining aquatic ecosystems , beavers especially . Aquatic mammals were the target for commercial industry , leading to a sharp decline in all populations of exploited species , such as beavers . Their pelts , suited for conserving heat , were taken during the fur trade and made into coats and hats . Other aquatic mammals , such as the Indian rhinoceros , were targets for sport hunting and had a sharp population decline in the 1900s . After it was made illegal , many aquatic mammals became subject to poaching . Other than hunting , aquatic mammals can be killed as bycatch from fisheries , where they become entangled in fixed netting and drown or starve . Increased river traffic , most notably in the Yangtze river , causes collisions between fast ocean vessels and aquatic mammals , and damming of rivers may land migratory aquatic mammals in unsuitable areas or destroy habitat upstream . The industrialization of rivers led to the extinction of the Chinese river dolphin , with the last confirmed sighting in 2004 . |
Arctic_Climate_Impact_Assessment | The Arctic Climate Impact Assessment ( ACIA ) is a study describing the ongoing climate change in the Arctic and its consequences : rising temperatures , loss of sea ice , unprecedented melting of the Greenland ice sheet , and many impacts on ecosystems , animals , and people . The ACIA is the first comprehensively researched , fully referenced , and independently reviewed evaluation of Arctic climate change and its impacts for the region and for the world . The project was guided by the intergovernmental Arctic Council and the non-governmental International Arctic Science Committee . Three hundred scientists participated in the study over a span of three years . The 140-page synthesis report Impacts of a Warming Arctic was released in November 2004 , and the scientific report later in 2005 . The ACIA Secretariat is located at the International Arctic Research Center at the University of Alaska Fairbanks . |
Antarctic_oscillation | The Antarctic oscillation ( AAO , to distinguish it from the Arctic oscillation or AO ) is a low-frequency mode of atmospheric variability of the southern hemisphere . It is also known as the Southern Annular Mode ( SAM ) . It is defined as a belt of westerly winds or low pressure surrounding Antarctica which moves north or south as its mode of variability . In its positive phase , the westerly wind belt contracts towards Antarctica , while its negative phase involves this belt moving towards the Equator . In 2014 , Dr Nerilie Abram used a network of temperature-sensitive ice core and tree growth records to reconstruct a 1000-year history of the Southern Annular Mode . This work suggests that the Southern Annular Mode is currently in its most extreme positive phase over at least the last 1000 years , and that recent positive trends in the SAM are attributed to increasing greenhouse gas levels and later stratospheric ozone depletion . |
Anecdotal_evidence | Anecdotal evidence is evidence from anecdotes , i.e. , evidence collected in a casual or informal manner and relying heavily or entirely on personal testimony . When compared to other types of evidence , anecdotal evidence is generally regarded as limited in value due to a number of potential weaknesses , but may be considered within the scope of scientific method as some anecdotal evidence can be both empirical and verifiable , e.g. in the use of case studies in medicine . Other anecdotal evidence , however , does not qualify as scientific evidence , because its nature prevents it from being investigated by the scientific method . Where only one or a few anecdotes are presented , there is a larger chance that they may be unreliable due to cherry-picked or otherwise non-representative samples of typical cases . Similarly , psychologists have found that due to cognitive bias people are more likely to remember notable or unusual examples rather than typical examples . Thus , even when accurate , anecdotal evidence is not necessarily representative of a typical experience . Accurate determination of whether an anecdote is `` typical '' requires statistical evidence . Misuse of anecdotal evidence is an informal fallacy and is sometimes referred to as the `` person who '' fallacy ( `` I know a person who ... '' ; `` I know of a case where ... '' etc. ) which places undue weight on experiences of close peers which may not be typical . Compare with hasty generalization . The term is sometimes used in a legal context to describe certain kinds of testimony which are uncorroborated by objective , independent evidence such as notarized documentation , photographs , audio-visual recordings , etc. . When used in advertising or promotion of a product , service , or idea , anecdotal reports are often called a testimonial , which are highly regulated or banned in some jurisdictions . |
Antarctic_Peninsula | The Antarctic Peninsula is the northernmost part of the mainland of Antarctica , located at the base of the Southern Hemisphere . At the surface , it is the biggest , most prominent peninsula in Antarctica as it extends 1300 km from a line between Cape Adams ( Weddell Sea ) and a point on the mainland south of Eklund Islands . Beneath the ice sheet which covers it , the Antarctic Peninsula consists of a string of bedrock islands ; these are separated by deep channels whose bottoms lie at depths considerably below current sea level . They are joined together by a grounded ice sheet . Tierra del Fuego , the southernmost tip of South America , lies only about 1000 km away across the Drake Passage . The Antarctic Peninsula is currently dotted with numerous research stations and nations have made multiple claims of sovereignty . The peninsula is part of disputed and overlapping claims by Argentina , Chile and the United Kingdom . None of these claims has international recognition and , under the Antarctic Treaty System , the respective countries do not attempt to enforce their claims . Argentina has the most bases and personnel stationed on the peninsula . |
Apologetics | Apologetics ( from Greek ἀπολογία , `` speaking in defense '' ) is the religious discipline of defending or proving the truth of religious doctrines through systematic argumentation and discourse . Early Christian writers ( c. 120 -- 220 ) who defended their beliefs against critics and recommended their faith to outsiders were called Christian apologists . In 21st century usage , ` apologetics ' is often identified with debates over religion and theology . |
Antithesis | Antithesis ( Greek for `` setting opposite '' , from ἀντί `` against '' and θέσις `` position '' ) is used in writing or speech either as a proposition that contrasts with or reverses some previously mentioned proposition , or when two opposites are introduced together for contrasting effect . Antithesis can be defined as `` a figure of speech involving a seeming contradiction of ideas , words , clauses , or sentences within a balanced grammatical structure . Parallelism of expression serves to emphasize opposition of ideas '' . An antithesis must always contain double meanings due to the reproduction of two ideas within one statement . The ideas may not be structurally opposite , but they serve to be functionally opposite when comparing two ideas for emphasis . According to Aristotle , the use of an antithesis makes the audience better understand the point one is trying to make through their argument . Further explained , the comparison of two situations or ideas makes choosing the correct one simpler . Aristotle states that antithesis in rhetoric is similar to syllogism due to the presentation of two conclusions within a statement . The term antithesis when used in speech is sometimes confused with the use of irony , or `` words -LSB- used -RSB- to convey a meaning opposite to their literal sense '' . The two are often mistaken for one another due to their creation of an opposite situation for the audience . The antithesis deals with two parallel ideas , whereas in irony , when used as a literary device , the words are implying an opposite idea directly through tone or word choice . To make the meaning more clear , consider this example of irony : I cut my hand on a Bandaid box . The example is not an antithesis because it does not present two parallel ideas , instead it gives an implication of the opposite idea through its tone . |
Anthropocentrism | Anthropocentrism ( -LSB- ˌænθroʊ-poʊ-ˈsɛntrɪzəm -RSB- from Greek ἄνθρωπος , ánthrōpos , `` human being '' ; and κέντρον , kéntron , `` center '' ) the belief that considers human beings to be the most significant entity of the universe and interprets or regards the world in terms of human values and experiences . The term can be used interchangeably with humanocentrism , and some refer to the concept as human supremacy or human exceptionalism . The mediocrity principle is the opposite of anthropocentrism . Anthropocentrism is considered to be profoundly embedded in many modern human cultures and conscious acts . It is a major concept in the field of environmental ethics and environmental philosophy , where it is often considered to be the root cause of problems created by human action within the ecosphere . However , many proponents of anthropocentrism state that this is not necessarily the case : they argue that a sound long-term view acknowledges that a healthy , sustainable environment is necessary for humans and that the real issue is shallow anthropocentrism . |
Astra_1K | Astra 1K was a communications satellite manufactured by Alcatel Space for SES . When it was launched on November 25 , 2002 it was the largest civilian communications satellite ever launched , with a mass of 5250 kg . Intended to replace the Astra 1B satellite and provide backup for 1A , 1C and 1D at the Astra 19.2 ° E orbital position , the Blok DM3 upper stage of the Proton launch vehicle failed to function properly , leaving the satellite in an unusable parking orbit . Although some attempts were made to `` rescue '' the satellite , it was intentionally de-orbited on December 10 , 2002 . The satellite featured frequency re-use for some of its transponders , using dual patterns coverage , one covering eastern Europe , the other covering Spain . This design was meant to cover specific markets only , in order to expand the capacity of the fleet , as frequency re-use enables more channels to be transmitted simultaneously at the same frequency , with the drawback that channels broadcast on the Spain beam would n't be receivable by any means ( no matter how large the receiving dish would be ) in the east beam and vice versa . This would have left for example the Netherlands and parts of neighbouring countries without reception of either of the beams , as the beams overlap over those countries , efficiently jamming each other . Astra 1K also featured multiple Ka Band capabilities , originally intended to provide an upload path for satellite internet services . SES later developed such a 2-way commercial satellite internet service with ASTRA2Connect , using Ku band for upload and download paths . A replacement craft , Astra 1KR was successfully launched in 2006 . |
Atlantic_hurricane | An Atlantic hurricane or tropical storm is a tropical cyclone that forms in the Atlantic Ocean , usually in the summer or fall . A hurricane differs from a cyclone or typhoon only on the basis of location . A hurricane is a storm that occurs in the Atlantic Ocean and northeastern Pacific Ocean , a typhoon occurs in the northwestern Pacific Ocean , and a cyclone occurs in the south Pacific or Indian Ocean . Tropical cyclones can be categorized by intensity . Tropical storms have one-minute maximum sustained winds of at least 39 mph ( 34 knots , 17 m/s , 63 km/h ) , while hurricanes have one-minute maximum sustained winds exceeding 74 mph ( 64 knots , 33 m/s , 119 km/h ) . Most North Atlantic tropical storms and hurricanes form between June 1 and November 30 . The United States National Hurricane Center monitors the basin and issues reports , watches , and warnings about tropical weather systems for the North Atlantic Basin as one of the Regional Specialized Meteorological Centers for tropical cyclones , as defined by the World Meteorological Organization . In recent times , tropical disturbances that reach tropical storm intensity are named from a predetermined list . Hurricanes that result in significant damage or casualties may have their names retired from the list at the request of the affected nations in order to prevent confusion should a subsequent storm be given the same name . On average , in the North Atlantic basin ( from 1966 to 2009 ) 11.3 named storms occur each season , with an average of 6.2 becoming hurricanes and 2.3 becoming major hurricanes ( Category 3 or greater ) . The climatological peak of activity is around September 11 each season . In March 2004 , Catarina was the first hurricane-intensity tropical cyclone ever recorded in the Southern Atlantic Ocean . Since 2011 , the Brazilian Navy Hydrographic Center has started to use the same scale of the North Atlantic Ocean for tropical cyclones in the South Atlantic Ocean and assign names to those which reach 35 kn . |
Asteroid | Asteroids are minor planets , especially those of the inner Solar System . The larger ones have also been called planetoids . These terms have historically been applied to any astronomical object orbiting the Sun that did not show the disc of a planet and was not observed to have the characteristics of an active comet . As minor planets in the outer Solar System were discovered and found to have volatile-based surfaces that resemble those of comets , they were often distinguished from asteroids of the asteroid belt . In this article , the term `` asteroid '' refers to the minor planets of the inner Solar System including those co-orbital with Jupiter . There are millions of asteroids , many thought to be the shattered remnants of planetesimals , bodies within the young Sun 's solar nebula that never grew large enough to become planets . The large majority of known asteroids orbit in the asteroid belt between the orbits of Mars and Jupiter , or are co-orbital with Jupiter ( the Jupiter trojans ) . However , other orbital families exist with significant populations , including the near-Earth objects . Individual asteroids are classified by their characteristic spectra , with the majority falling into three main groups : C-type , M-type , and S-type . These were named after and are generally identified with carbon-rich , metallic , and silicate ( stony ) compositions , respectively . The size of asteroids varies greatly , some reaching as much as across . Asteroids are differentiated from comets and meteoroids . In the case of comets , the difference is one of composition : while asteroids are mainly composed of mineral and rock , comets are composed of dust and ice . In addition , asteroids formed closer to the sun , preventing the development of the aforementioned cometary ice . The difference between asteroids and meteoroids is mainly one of size : meteoroids have a diameter of less than one meter , whereas asteroids have a diameter of greater than one meter . Finally , meteoroids can be composed of either cometary or asteroidal materials . Only one asteroid , 4 Vesta , which has a relatively reflective surface , is normally visible to the naked eye , and this only in very dark skies when it is favorably positioned . Rarely , small asteroids passing close to Earth may be visible to the naked eye for a short time . As of March 2016 , the Minor Planet Center had data on more than 1.3 million objects in the inner and outer Solar System , of which 750,000 had enough information to be given numbered designations . The United Nations declared June 30 as International Asteroid Day to educate the public about asteroids . The date of International Asteroid Day commemorates the anniversary of the Tunguska asteroid impact over Siberia , Russian Federation , on 30 June 1908 . |
Atmospheric_duct | In telecommunication , an atmospheric duct is a horizontal layer in the lower atmosphere in which the vertical refractive index gradients are such that radio signals ( and light rays ) are guided or ducted , tend to follow the curvature of the Earth , and experience less attenuation in the ducts than they would if the ducts were not present . The duct acts as an atmospheric dielectric waveguide and limits the spread of the wavefront to only the horizontal dimension . Atmospheric ducting is a mode of propagation of electromagnetic radiation , usually in the lower layers of Earth 's atmosphere , where the waves are bent by atmospheric refraction . In over-the-horizon radar , ducting causes part of the radiated and target-reflection energy of a radar system to be guided over distances far greater than the normal radar range . It also causes long distance propagation of radio signals in bands that would normally be limited to line of sight . Normally radio `` ground waves '' propagate along the surface as creeping waves . That is , they are only diffracted around the curvature of the earth . This is one reason that early long distance radio communication used long wavelengths . The best known exception is that HF ( 3 -- 30 MHz . ) waves are reflected by the ionosphere . The reduced refractive index due to lower densities at the higher altitudes in the Earth 's atmosphere bends the signals back toward the Earth . Signals in a higher refractive index layer , i.e. , duct , tend to remain in that layer because of the reflection and refraction encountered at the boundary with a lower refractive index material . In some weather conditions , such as inversion layers , density changes so rapidly that waves are guided around the curvature of the earth at constant altitude . Phenomena of atmospheric optics related to atmospheric ducting include the green flash , Fata Morgana , superior mirage , mock mirage of astronomical objects and the Novaya Zemlya effect . |
Baja_California | Baja California , ( Lower California ) , officially the Free and Sovereign State of Baja California ( Estado Libre y Soberano de Baja California ) , is a state in Mexico . It is the northernmost and westernmost of the 32 Federal Entities of Mexico . Before becoming a state in 1952 , the area was known as the North Territory of Baja California ( El Territorio Norte de Baja California ) . It has an area of 70113 km2 , or 3.57 % of the land mass of Mexico and comprises the northern half of the Baja California Peninsula , north of the 28th parallel , plus oceanic Guadalupe Island . The mainland portion of the state is bordered on the west by the Pacific Ocean , on the east by Sonora , the U.S. State of Arizona , and the Gulf of California ( also known as the `` Sea of Cortez '' ) , and on the south by Baja California Sur . Its northern limit is the U.S. state of California . The state has an estimated population of 3,315,766 ( 2015 ) much more than the sparsely populated Baja California Sur to the south , and similar to San Diego County , California on its north . Over 75 % of the population lives in the capital city , Mexicali , in Ensenada , or in Tijuana . Other important cities include San Felipe , Rosarito and Tecate . The population of the state is composed of Mestizos , mostly immigrants from other parts of Mexico , and , as with most northern Mexican states , a large population of Mexicans of Spanish ancestry , and also a large minority group of East Asian , Middle Eastern and indigenous descent . Additionally , there is a large immigrant population from the United States due to its proximity to San Diego and the cheaper cost of living compared to San Diego . There is also a significant population from Central America . Many immigrants moved to Baja California for a better quality of life and the number of higher paying jobs in comparison to the rest of Mexico and Latin America . Baja California is the twelfth largest state by area in Mexico . Its geography ranges from beaches to forests and deserts . The backbone of the state is the Sierra de Baja California , where the Picacho del Diablo , the highest point of the peninsula , is located . This mountain range effectively divides the weather patterns in the state . In the northwest , the weather is semi-dry and mediterranean . In the narrow center , the weather changes to be more humid due to altitude . It is in this area where a few valleys can be found , such as the Valle de Guadalupe , the major wine producing area in Mexico . To the east of the mountain range , the Sonoran Desert dominates the landscape . In the south , the weather becomes drier and gives way to the Vizcaino Desert . The state is also home to numerous islands off both of its shores . In fact , the westernmost point in Mexico , the Guadalupe Island , is part of Baja California . The Coronado , Todos Santos and Cedros Islands are also on the Pacific Shore . On the Gulf of California , the biggest island is the Angel de la Guarda , separated from the peninsula by the deep and narrow Canal de Ballenas . |
BBC_Earth | BBC Earth is a brand used by BBC Worldwide since 2009 to market and distribute the BBC 's natural history content to countries other than the United Kingdom . BBC Worldwide is the commercial arm of the public service broadcaster . BBC Earth commercially represents the BBC Natural History Unit , the largest wildlife documentary production house in the world . BBC Earth is responsible for the worldwide marketing and distribution of titles such as Frozen Planet , Life , Blue Planet , and Planet Earth . It has generated sales to over 180 countries . The BBC Earth brand is used across a range of media platforms , including concert-style documentary viewings with a live orchestra and interactive experiences at museums and theme parks . Its website was relaunched in 2010 incorporating a new consumer-facing site `` Life Is '' which features a bi-monthly magazine style update and a blog . The brand is also used for new releases of BBC natural history titles on DVD and Blu-ray . |
Automatic_weather_station | An automatic weather station ( AWS ) is an automated version of the traditional weather station , either to save human labour or to enable measurements from remote areas . An AWS will typically consist of a weather-proof enclosure containing the data logger , rechargeable battery , telemetry ( optional ) and the meteorological sensors with an attached solar panel or wind turbine and mounted upon a mast . The specific configuration may vary due to the purpose of the system . The system may report in near real time via the Argos System and the Global Telecommunications System , or save the data for later recovery . In the past , automatic weather stations were often placed where electricity and communication lines were available . Nowadays , the solar panel , wind turbine and mobile phone technology have made it possible to have wireless stations that are not connected to the electrical grid or hardline telecommunications network . |
Artificial_photosynthesis | Artificial photosynthesis is a chemical process that replicates the natural process of photosynthesis , a process that converts sunlight , water , and carbon dioxide into carbohydrates and oxygen ; as an imitation of a natural process it is biomimetic . The term , artificial photosynthesis , is commonly used to refer to any scheme for capturing and storing the energy from sunlight in the chemical bonds of a fuel ( a solar fuel ) . Photocatalytic water splitting converts water into hydrogen ions and oxygen , and is a major research topic of artificial photosynthesis . Light-driven carbon dioxide reduction is another process studied , that replicates natural carbon fixation . Research of this topic includes the design and assembly of devices for the direct production of solar fuels , photoelectrochemistry and its application in fuel cells , and the engineering of enzymes and photoautotrophic microorganisms for microbial biofuel and biohydrogen production from sunlight . |
Autoimmunity | Autoimmunity is the system of immune responses of an organism against its own healthy cells and tissues . Any disease that results from such an aberrant immune response is termed an autoimmune disease . Prominent examples include celiac disease , diabetes mellitus type 1 , sarcoidosis , systemic lupus erythematosus ( SLE ) , Sjögren 's syndrome , eosinophilic granulomatosis with polyangiitis , Hashimoto 's thyroiditis , Graves ' disease , idiopathic thrombocytopenic purpura , Addison 's disease , rheumatoid arthritis ( RA ) , ankylosing spondylitis , polymyositis ( PM ) , and dermatomyositis ( DM ) . Autoimmune diseases are very often treated with steroids . The misconception that an individual 's immune system is totally incapable of recognizing self antigens is not new . Paul Ehrlich , at the beginning of the twentieth century , proposed the concept of horror autotoxicus , wherein a `` normal '' body does not mount an immune response against its own tissues . Thus , any autoimmune response was perceived to be abnormal and postulated to be connected with human disease . Now , it is accepted that autoimmune responses are an integral part of vertebrate immune systems ( sometimes termed `` natural autoimmunity '' ) , normally prevented from causing disease by the phenomenon of immunological tolerance to self-antigens . Autoimmunity should not be confused with alloimmunity . |
Attribution_of_recent_climate_change | Attribution of recent climate change is the effort to scientifically ascertain mechanisms responsible for recent climate changes on Earth , commonly known as ` global warming ' . The effort has focused on changes observed during the period of instrumental temperature record , when records are most reliable ; particularly in the last 50 years , when human activity has grown fastest and observations of the troposphere have become available . The dominant mechanisms are anthropogenic , i.e. , the result of human activity . They are : increasing atmospheric concentrations of greenhouse gases global changes to land surface , such as deforestation increasing atmospheric concentrations of aerosols . There are also natural mechanisms for variation including climate oscillations , changes in solar activity , and volcanic activity . According to the Intergovernmental Panel on Climate Change ( IPCC ) , it is `` extremely likely '' that human influence was the dominant cause of global warming between 1951 and 2010 . The IPCC defines `` extremely likely '' as indicating a probability of 95 to 100 % , based on an expert assessment of all the available evidence . Multiple lines of evidence support attribution of recent climate change to human activities : A basic physical understanding of the climate system : greenhouse gas concentrations have increased and their warming properties are well-established . Historical estimates of past climate changes suggest that the recent changes in global surface temperature are unusual . Computer-based climate models are unable to replicate the observed warming unless human greenhouse gas emissions are included . Natural forces alone ( such as solar and volcanic activity ) can not explain the observed warming . The IPCC 's attribution of recent global warming to human activities is a view shared by the scientific community , and is also supported by 196 other scientific organizations worldwide ( see also : scientific opinion on climate change ) . |
Barack_Obama | Barack Hussein Obama II ( -LSB- bəˈrɑːk_huːˈseɪn_oʊˈbɑːmə -RSB- ; born August 4 , 1961 ) is an American politician who served as the 44th President of the United States from 2009 to 2017 . He is the first African American to have served as president . He previously served in the U.S. Senate representing Illinois from 2005 to 2008 , and in the Illinois State Senate from 1997 to 2004 . Obama was born in Honolulu , Hawaii , two years after the territory was admitted to the Union as the 50th state . Raised largely in Hawaii , Obama also spent one year of his childhood in Washington State and four years in Indonesia . After graduating from Columbia University in 1983 , he worked as a community organizer in Chicago . In 1988 Obama enrolled in Harvard Law School , where he was the first black president of the Harvard Law Review . After graduation , he became a civil rights attorney and professor , teaching constitutional law at the University of Chicago Law School from 1992 to 2004 . Obama represented the 13th District for three terms in the Illinois Senate from 1997 to 2004 , when he ran for the U.S. Senate . Obama received national attention in 2004 , with his unexpected March primary win , his well-received July Democratic National Convention keynote address , and his landslide November election to the Senate . In 2008 , Obama was nominated for president , a year after his campaign began , and after a close primary campaign against Hillary Clinton . He was elected over Republican John McCain , and was inaugurated on January 20 , 2009 . Nine months later , Obama was named the 2009 Nobel Peace Prize laureate . During his first two years in office , Obama signed many landmark bills . Main reforms were the Patient Protection and Affordable Care Act ( often referred to as `` Obamacare '' ) , the Dodd -- Frank Wall Street Reform and Consumer Protection Act , and the Do n't Ask , Do n't Tell Repeal Act of 2010 . The American Recovery and Reinvestment Act of 2009 and Tax Relief , Unemployment Insurance Reauthorization , and Job Creation Act of 2010 served as economic stimulus amidst the Great Recession , but the GOP regained control of the House of Representatives in 2011 . After a lengthy debate over the national debt limit , Obama signed the Budget Control and the American Taxpayer Relief Acts . In foreign policy , Obama increased U.S. troop levels in Afghanistan , reduced nuclear weapons with the U.S.-Russian New START treaty , and ended military involvement in the Iraq War . He ordered military involvement in Libya in opposition to Muammar Gaddafi , and the military operation that resulted in the death of Osama bin Laden . After winning re-election by defeating Republican nominee Mitt Romney , Obama was sworn in for a second term in 2013 . During his second term , Obama promoted greater inclusiveness for LGBT Americans , with his administration filing briefs that urged the Supreme Court to strike down same-sex marriage bans as unconstitutional ( United States v. Windsor and Obergefell v. Hodges ) . Obama also advocated gun control in response to the Sandy Hook Elementary School shooting , and issued wide-ranging executive actions concerning climate change and immigration . In foreign policy , Obama ordered military intervention in Iraq in response to gains made by ISIL after the 2011 withdrawal from Iraq , continued the process of ending U.S. combat operations in Afghanistan , promoted discussions that led to the 2015 Paris Agreement on global climate change , initiated the sanctions against Russia following the invasion in Ukraine , brokered a nuclear deal with Iran , and normalized U.S. relations with Cuba . Obama left office in January 2017 with a 60 % approval rating . He currently resides in Washington , D.C. His presidential library will be built in Chicago . |
Astrophysics | Astrophysics is the branch of astronomy that employs the principles of physics and chemistry `` to ascertain the nature of the heavenly bodies , rather than their positions or motions in space . '' Among the objects studied are the Sun , other stars , galaxies , extrasolar planets , the interstellar medium and the cosmic microwave background . Their emissions are examined across all parts of the electromagnetic spectrum , and the properties examined include luminosity , density , temperature , and chemical composition . Because astrophysics is a very broad subject , astrophysicists typically apply many disciplines of physics , including mechanics , electromagnetism , statistical mechanics , thermodynamics , quantum mechanics , relativity , nuclear and particle physics , and atomic and molecular physics . In practice , modern astronomical research often involves a substantial amount of work in the realms of theoretical and observational physics . Some areas of study for astrophysicists include their attempts to determine : the properties of dark matter , dark energy , and black holes ; whether or not time travel is possible , wormholes can form , or the multiverse exists ; and the origin and ultimate fate of the universe . Topics also studied by theoretical astrophysicists include : Solar System formation and evolution ; stellar dynamics and evolution ; galaxy formation and evolution ; magnetohydrodynamics ; large-scale structure of matter in the universe ; origin of cosmic rays ; general relativity and physical cosmology , including string cosmology and astroparticle physics . |
Balance_of_nature | The balance of nature is a theory that proposes that ecological systems are usually in a stable equilibrium or homeostasis , which is to say that a small change in some particular parameter ( the size of a particular population , for example ) will be corrected by some negative feedback that will bring the parameter back to its original `` point of balance '' with the rest of the system . It may apply where populations depend on each other , for example in predator/prey systems , or relationships between herbivores and their food source . It is also sometimes applied to the relationship between the Earth 's ecosystem , the composition of the atmosphere , and the world 's weather . The Gaia hypothesis is a balance of nature-based theory that suggests that the Earth and its ecology may act as co-ordinated systems in order to maintain the balance of nature . The theory that nature is permanently in balance has been largely discredited , as it has been found that chaotic changes in population levels are common , but nevertheless the idea continues to be popular . During the later half of the twentieth century the theory was superseded by catastrophe theory and chaos theory . |
Asia | Asia is Earth 's largest and most populous continent , located primarily in the eastern and northern hemispheres and sharing the continental landmass of Eurasia with the continent of Europe and shares the continental landmass of Afro-Eurasia with both Europe and Africa . Asia covers an area of 44,579,000 km2 , about 30 % of Earth 's total land area and 8.7 % of the Earth 's total surface area . The continent , which has long been home to the majority of the human population , was the site of many of the first civilizations . Asia is notable for not only its overall large size and population , but also dense and large settlements as well as vast barely populated regions within the continent of 4.4 billion people . In general terms , Asia is bounded on the east by the Pacific Ocean , on the south by the Indian Ocean and on the north by the Arctic Ocean . The western boundary with Europe is a historical and cultural construct , as there is no clear physical and geographical separation between them . The most commonly accepted boundaries place Asia to the east of the Suez Canal , the Ural River , and the Ural Mountains , and south of the Caucasus Mountains and the Caspian and Black Seas . China and India alternated in being the largest economies in the world from 1 to 1800 CE . China was a major economic power and attracted many to the east , and for many the legendary wealth and prosperity of the ancient culture of India personified Asia , attracting European commerce , exploration and colonialism . The accidental discovery of America by Columbus in search for India demonstrates this deep fascination . The Silk Road became the main East-West trading route in the Asian hitherland while the Straits of Malacca stood as a major sea route . Asia has exhibited economic dynamism ( particularly East Asia ) as well as robust population growth during the 20th century , but overall population growth has since fallen . Asia was the birthplace of most of the world 's mainstream religions including Christianity , Islam , Judaism , Hinduism , Buddhism , Confucianism , Taoism ( or Daoism ) , Jainism , Sikhism , Zoroastranism , as well as many other religions . Given its size and diversity , the concept of Asia -- a name dating back to classical antiquity -- may actually have more to do with human geography than physical geography . Asia varies greatly across and within its regions with regard to ethnic groups , cultures , environments , economics , historical ties and government systems . It also has a mix of many different climates ranging from the equatorial south via the hot desert in the Middle East , temperate areas in the east and the continental centre to vast subarctic and polar areas in Siberia . |
Atlantic_Seaboard_fall_line | The Atlantic Seaboard Fall Line , or Fall Zone , is a 900 mi escarpment where the Piedmont and Atlantic coastal plain meet in the eastern United States . Much of the Atlantic Seaboard fall line passes through areas where no evidence of faulting is present . The fall line marks the geologic boundary of hard metamorphosed terrain -- the product of the Taconic orogeny -- and the sandy , relatively flat outwash plain of the upper continental shelf , formed of unconsolidated Cretaceous and Cenozoic sediments . Examples of the Fall Zone include the Potomac River 's Little Falls and the rapids in Richmond , Virginia , where the James River falls across a series of rapids down to its own tidal estuary . Before navigation improvements such as locks , the fall line was generally the head of navigation on rivers due to their rapids or waterfalls , and the necessary portage around them . The Little Falls of the Potomac River is one example . Because of the commercial traffic , required labor and availability of water power to operate mills , numerous cities were founded at the intersection of rivers and the fall line . U.S. Route 1 links many of the fall line cities . In 1808 , Treasury Secretary Albert Gallatin noted the significance of the fall line as an obstacle to improved national communication and commerce between the Atlantic seaboard and the western river systems : |
Bandwagon_effect | The bandwagon effect is a phenomenon whereby the rate of uptake of beliefs , ideas , fads and trends increases the more that they have already been adopted by others . In other words , the bandwagon effect is characterized by the probability of individual adoption increasing with respect to the proportion who have already done so . As more people come to believe in something , others also `` hop on the bandwagon '' regardless of the underlying evidence . The tendency to follow the actions or beliefs of others can occur because individuals directly prefer to conform , or because individuals derive information from others . Both explanations have been used for evidence of conformity in psychological experiments . For example , social pressure has been used to explain Asch 's conformity experiments , and information has been used to explain Sherif 's autokinetic experiment . According to this concept , the increasing popularity of a product or phenomenon encourages more people to `` get on the bandwagon '' , too . The bandwagon effect explains why there are fashion trends . When individuals make rational choices based on the information they receive from others , economists have proposed that information cascades can quickly form in which people decide to ignore their personal information signals and follow the behavior of others . Cascades explain why behavior is fragile -- people understand that they are based on very limited information . As a result , fads form easily but are also easily dislodged . Such informational effects have been used to explain political bandwagons . |
Atlantic_coastal_plain | The Atlantic coastal plain is a physiographic region of low relief along the East Coast of the United States . It extends 2200 mi from the New York Bight southward to a Georgia/Florida section of the Eastern Continental Divide , which demarcates the plain from the ACF River Basin in the Gulf Coastal Plain to the west . The province is bordered on the west by the Atlantic Seaboard fall line and the Piedmont plateau , to the east by the Atlantic Ocean , and to the south by the Floridian province . The Outer Lands archipelagic region forms the insular northeasternmost extension of the Atlantic coastal plain . The province 's average elevation is less than 900 meters above sea level and extends some 50 to 100 kilometers inland from the ocean . The coastal plain is normally wet , including many rivers , marsh , and swampland . It is composed primarily of sedimentary rock and unlithified sediments and is primarily used for agriculture . The area is subdivided into the Embayed and Sea Island physiographic provinces , as well as the Mid-Atlantic and South Atlantic coastal plains . |
Autumn | Autumn ( British English ) or fall ( American English ) is one of the four temperate seasons . Autumn marks the transition from summer to winter , in September ( Northern Hemisphere ) or March ( Southern Hemisphere ) , when the arrival of night becomes noticeably earlier and the arrival of day becomes noticeably later , and the temperature cools down considerably . One of its main features is the shedding of leaves from deciduous trees . Some cultures regard the autumnal equinox as `` mid-autumn '' , while others with a longer temperature lag treat it as the start of autumn . Meteorologists ( and most of the temperate countries in the southern hemisphere ) use a definition based on months , with autumn being September , October and November in the northern hemisphere , and March , April and May in the southern hemisphere . In North America , autumn is usually considered to start with the September equinox ( 21 to 24 September ) and end with the winter solstice ( 21 or 22 December ) . Popular culture in North America associates Labor Day , the first Monday in September , as the end of summer and the start of autumn ; certain summer traditions , such as wearing white , are discouraged after that date . As daytime and nighttime temperatures decrease , trees shed their leaves . In traditional East Asian solar term , autumn starts on or around 8 August and ends on or about 7 November . In Ireland , the autumn months according to the national meteorological service , Met Éireann , are September , October and November . However , according to the Irish Calendar , which is based on ancient Gaelic traditions , autumn lasts throughout the months of August , September and October , or possibly a few days later , depending on tradition . In Australia and New Zealand , autumn officially begins on 1 March and ends on 31 May . |
Associated_Press | The Associated Press ( AP ) is an American multinational nonprofit news agency headquartered in New York City that operates as a cooperative , unincorporated association . The AP is owned by its contributing newspapers and radio and television stations in the United States , all of which contribute stories to the AP and use material written by its staff journalists . Most of the AP staff are union members and are represented by the Newspaper Guild , which operates under the Communications Workers of America , which operates under the AFL -- CIO . As of 2007 , news collected by the AP was published and republished by more than 1,700 newspapers , in addition to more than 5,000 television and radio broadcasters . The photograph library of the AP consists of over 10 million images . The AP operates 243 news bureaus in 120 countries . It also operates the AP Radio Network , which provides newscasts twice hourly for broadcast and satellite radio and television stations . Many newspapers and broadcasters outside the United States are AP subscribers , paying a fee to use AP material without being contributing members of the cooperative . As part of their cooperative agreement with the AP , most member news organizations grant automatic permission for the AP to distribute their local news reports . The AP employs the `` inverted pyramid '' formula for writing that enables the news outlets to edit a story to fit its available publication area without losing the story 's essentials . Cutbacks at rival United Press International in 1993 left the AP as the United States ' primary news service , although UPI still produces and distributes stories and photos daily . Other English-language news services , such as the BBC , Reuters and the English-language service of Agence France-Presse , are based outside the United States . |