Albany, New York

Albany ( -LSB- ˈɔːlbəni -RSB- ) is the capital of the U.S. state of New York and the seat of Albany County . Roughly 150 mi north of New York City , Albany developed on the west bank of the Hudson River , about 10 mi south of its confluence with the Mohawk River . The population of the City of Albany was 97,856 according to the 2010 census . Albany constitutes the economic and cultural core of the Capital District of New York State , which comprises the Albany-Schenectady-Troy , NY Metropolitan Statistical Area , including the nearby cities and suburbs of Troy , Schenectady , and Saratoga Springs . With a 2013 Census-estimated population of 1.1 million the Capital District is the third-most populous metropolitan region in the state and 38th in the United States .   Fortune 500 companies with offices in Albany include American Express , J.P. Morgan and Chase , Merrill Lynch , General Electric , Verizon , Goldman Sachs , International Paper , and Key Bank . In the 21st century , the Capital District has emerged as a major anchor of Tech Valley , the moniker describing the technologically-focused region of eastern New York State .   This was the first European settlement in the state . It was settled by Dutch colonists who in 1614 , built Fort Nassau for fur trading and Fort Orange in 1624 . They formed successful relations with both the Mahican and the Mohawk peoples , two major Native American nations in the region . The fur trade attracted settlers who founded a village called Beverwijck near Fort Orange . In 1664 the English took over the Dutch settlements , renaming the city as Albany , in honor of the then Duke of Albany , the future James II of England and James VII of Scotland . The city was officially chartered in 1686 under English rule . It became the capital of New York State in 1797 , following the United States gaining independence in the American Revolutionary War . Albany is one of the oldest surviving settlements of the original British thirteen colonies , and the longest continuously chartered city in the United States . Its charter is possibly the longest-running instrument of municipal government in the Western Hemisphere .   During the late 18th century and throughout most of the 19th , Albany was a center of trade and transportation . It is on the north end of the navigable Hudson River , was the original eastern terminus of the Erie Canal connecting to the Great Lakes , and was home to some of the earliest railroad systems in the world . Albany 's main exports at the time were beer , lumber , published works , and ironworks . Beginning in 1810 , Albany was one of the ten most populous cities in the United States , a distinction it held until the 1860 census .   Albany is one of the first cities in the world to have installed public water mains , sewer lines , natural gas lines and electricity , infrastructure and utilities that attracted and supported substantial new industry to the city and surrounding area during the 19th century .   In the 20th century , the city opened one of the first commercial airports in the world , the precursor of today 's Albany International Airport . During the 1920s a powerful political machine controlled by the Democratic Party arose in the state capital , connected to politics in New York City as well . It marshalled the power of immigrants and their descendants in both cities .   The city 's skyline changed in the 1960s and 1970s with the construction of office towers around the Empire State Plaza and at the uptown campus of SUNY Albany , mainly under the direction of Governor Nelson Rockefeller . While Albany experienced a decline in its population due to urban sprawl and suburbanization , many of its historic neighborhoods were saved from destruction through the policies of Mayor Erastus Corning 2nd , the longest-serving mayor of any city in the United States . In the early 21st century , Albany has experienced growth in the high-technology industry , with great strides in the nanotechnology sector .   Albany has been a center of higher education for over a century , with much of the remainder of its economy dependent on state government and health care services . The city has rebounded from the urban decline of the 1970s and 1980s , with noticeable development taking place in the city 's downtown and midtown neighborhoods . Albany is known for its rich history , commerce , culture , architecture , and institutions of higher education . Albany won the All-America City Award in both 1991 and 2009 .


Albedo

Albedo ( -LSB- ælˈbiːdoʊ -RSB- ) is a measure for reflectance or optical brightness ( Latin albedo , Arabic albayad , `` whiteness '' ) . It is dimensionless and measured on a scale from zero ( corresponding to a black body that absorbs all incident radiation ) to one ( corresponding to a white body that reflects all incident radiation ) .   Surface albedo is defined as the ratio of radiation reflected to the radiation incident on a surface . The proportion reflected is not only determined by properties of the surface itself , but also by the spectral and angular distribution of solar radiation reaching the Earth 's surface . These factors vary with atmospheric composition , geographic location and time ( see Position of the Sun ) . While bi-hemispherical reflectance is calculated for a single angle of incidence ( i.e. , for a given position of the sun ) , albedo is the directional integration of reflectance over all solar angles in a given period . The temporal resolution may range from seconds ( as obtained from flux measurements ) to daily , seasonal or annual averages .   Unless given for a specific wavelength ( spectral albedo ) , albedo refers to the entire spectrum of solar radiation . Due to measurement constraints , it is often given for the spectrum in which most solar energy reaches the surface ( approximately between 0.3 and 3 μm ) . This spectrum includes visible light ( 0.39-0 .7 μm ) , which explains why surfaces with a low albedo appear dark ( e.g. , trees absorb most radiation ) , whereas surfaces with a high albedo appear bright ( e.g. , snow reflects most radiation ) .   Albedo is an important concept in climatology , astronomy , and environmental management ( e.g. , as part of the Leadership in Energy and Environmental Design ( LEED ) program for sustainable rating of buildings ) . The average albedo of the Earth at the top of the atmosphere , its planetary albedo , is 30 to 35 % because of cloud cover , but widely varies locally across the surface because of different geological and environmental features .   The term albedo was introduced into optics by Johann Heinrich Lambert in his 1760 work Photometria .


Alcoa

Alcoa Corporation ( from Aluminum Company of America ) is an American industrial corporation . It is the world 's fifth largest producer of aluminum , with corporate headquarters in New York City . From its operational base in Pittsburgh , Pennsylvania in the United States , Alcoa conducts operations in 10 countries . Alcoa is a major producer of primary aluminum , fabricated aluminum , and alumina combined , through its active and growing participation in all major aspects of the industry : technology , mining , refining , smelting , fabricating , and recycling .   In May 2007 Alcoa Inc. made a US$ 27 billion hostile takeover bid for Alcan in an attempt to form the world 's largest aluminum producer . The bid was withdrawn when Alcan announced a friendly takeover by Rio Tinto in July 2007 .   On November 1 , 2016 , Alcoa Inc. split into two new entities : Alcoa Corporation , which is engaged in the mining and manufacture of raw aluminum , and Arconic , which processes aluminum and other metals .   In April 2017 , Alcoa announced it will move its headquarters back to Pittsburgh effective September 1 .


Alcohol (drug)

Alcohol, sometimes referred to by the chemical name ethanol, is a psychoactive drug that is the active ingredient in drinks such as beer, wine, and distilled spirits (hard liquor). It is one of the oldest and most common recreational substances, causing the characteristic effects of alcohol intoxication ("drunkenness"). Among other effects, alcohol produces a mood lift and euphoria, decreased anxiety, increased sociability, sedation, impairment of cognitive, memory, motor, and sensory function, and generalized depression of central nervous system function. Ethanol is only one of several types of alcohol, but it is the only type of alcohol that is found in alcoholic beverages or commonly used for recreational purposes; other alcohols such as methanol and isopropyl alcohol are significantly more toxic.  A mild, brief exposure to isopropanol, being only moderately more toxic than ethanol, is unlikely to cause any serious harm.  Methanol, being profoundly more toxic than ethanol, is lethal in quantities as small as 10–15 milliliters (2–3 tsp). Alcohol has a variety of short-term and long-term adverse effects. Short-term adverse effects include generalized impairment of neurocognitive function, dizziness, nausea, vomiting, and hangover-like symptoms. Alcohol can be addictive to humans, as in alcoholism, and can result in dependence and withdrawal. It can have a variety of long-term adverse effects on health, for instance liver damage, brain damage, and its consumption is the fifth leading cause of cancer. The adverse effects of alcohol on health are most important when it is used in excessive quantities or with heavy frequency. However, some of them, such as increased risk of certain cancers, may occur even with light or moderate alcohol consumption. In high amounts, alcohol may cause loss of consciousness or, in severe cases, death. Alcohol works in the brain primarily by increasing the effects of a neurotransmitter called γ-aminobutyric acid, or GABA. This is the major inhibitory neurotransmitter in the brain, and by facilitating its actions, alcohol suppresses the activity of the central nervous system. The substance also directly affects a number of other neurotransmitter systems including those of glutamate, glycine, acetylcholine, and serotonin. The pleasurable effects of alcohol ingestion are the result of increased levels of dopamine and endogenous opioids in the reward pathways of the brain. Alcohol also has toxic and unpleasant actions in the body, many of which are mediated by its byproduct acetaldehyde.Alcohol has been produced and consumed by humans for its psychoactive effects for almost 10,000 years. Drinking alcohol is generally socially acceptable and is legal in most countries, unlike with many other recreational substances. However, there are often restrictions on alcohol sale and use, for instance a minimum age for drinking and laws against public drinking and drinking and driving. Alcohol has considerable societal and cultural significance and has important social roles in much of the world. Drinking establishments, such as bars and nightclubs, revolve primarily around the sale and consumption of alcoholic beverages, and parties, festivals, and social gatherings commonly involve alcohol consumption. Its use is also related to various societal problems, including driving accidents and fatalities, accidental injuries, sexual assaults, domestic abuse, and violent crime. Alcohol remains illegal for sale and consumption in a number of countries, mainly in the Middle East.


Alentejo

Alentejo is a geographical , historical and cultural region of south-central and southern Portugal . Literally , in Portuguese it means `` beyond '' ( além ) Tagus river ( Tejo ) .   Alentejo includes the regions of Alto Alentejo and Baixo Alentejo . It corresponds to the districts of Beja , Évora , Portalegre and the Alentejo Litoral . The main cities are : Évora , Beja , Serpa , Estremoz , Elvas and Portalegre .   It has borders with Beira Baixa in the North , with Spain ( Andalucia and Extremadura in the east , with Algarve in the South and with the Atlantic Ocean , Ribatejo and Estremadura in the West .   The Alentejo is a region known for its traditional polyphonic singing groups , similar to those found in Tuscany , Corsica , and elsewhere .


Alf Ramsey

Sir Alfred Ernest `` Alf '' Ramsey ( 22 January 1920 -- 28 April 1999 ) was an English football player and manager who , as manager of the England national football team from 1963 to 1974 , guided England to victory in the 1966 FIFA World Cup . Knighted in 1967 in recognition of England 's World Cup win , Ramsey also managed England to third place in the 1968 European Championship and the quarter-finals of the 1970 World Cup and the 1972 European Championship respectively . As a player , Ramsey was a defender and a member of England 's 1950 World Cup squad . He is , , the only person to have been inducted into the English Football Hall of Fame twice , both as manager and player .   Ramsey was born and raised in Dagenham , which was then a quiet Essex village . He showed sporting promise from an early age and , after serving in the British Army during the Second World War , embarked on a football career , primarily as a right-back for Southampton and Tottenham Hotspur . He was generally considered a rather slow , but accomplished player with a tremendous grasp of the tactical side of the game . Nicknamed `` The General '' , he was part of the Tottenham side that won the English League championship in the 1950 -- 51 season ; he also played for England 32 times between 1948 and 1953 , captaining the side three times and scoring three goals from penalty kicks . England games in which Ramsey played include the shock 1 -- 0 defeat to the United States at the 1950 World Cup and the `` Match of the Century '' against Hungary three years later .   Ramsey retired from playing in 1955 to become the manager of Ipswich Town , then in the third tier of English football . Ipswich rose through the divisions over the next six years , winning the Third Division South in 1956 -- 57 and the Second Division in 1960 -- 61 . In the 1961 -- 62 season , Ipswich 's first campaign in the top division , Ramsey 's team defied expectations to become champions of England at the first attempt . Ramsey took charge of the England team a year later . In a distinct break with common practice of the day , he used a narrow formation that led to his England side being dubbed `` The Wingless Wonders '' . England 's World Cup victory at Wembley in 1966 made Ramsey a national hero , though he had his critics , both at the time and since . He lost the England job acrimoniously , following the team 's failure to qualify for the 1974 World Cup .   After briefly managing Birmingham City during the 1977 -- 78 season , then acting in an advisory role at the Greek club Panathinaikos in 1979 -- 80 , Ramsey retired to Ipswich , where he led a somewhat reclusive life over the next two decades . He died in Ipswich in 1999 , aged 79 . Soon after his death , a statue of Ramsey was built outside Ipswich 's home ground at Portman Road , and a neighbouring street was named after him . A stand at Portman Road was named after Ramsey in 2012 . A second statue of Ramsey was dedicated at the reconstructed Wembley Stadium in 2009 , in the players ' tunnel . Ramsey was an inaugural inductee into the English Football Hall of Fame in 2002 , in recognition of his achievements as a manager ; he was admitted again , as a player , in 2010 . He remains widely regarded as one of British football 's all-time great managers .


Algae

Algae ( -LSB- ˈældʒi , _ ˈælɡi -RSB- singular alga -LSB- ˈælɡə -RSB- ) is an informal term for a large , diverse group of photosynthetic organisms which are not necessarily closely related , and is thus polyphyletic . Included organisms range from unicellular genera , such as Chlorella and the diatoms , to multicellular forms , such as the giant kelp , a large brown alga which may grow up to 50 m in length . Most are aquatic and autotrophic and lack many of the distinct cell and tissue types , such as stomata , xylem , and phloem , which are found in land plants . The largest and most complex marine algae are called seaweeds , while the most complex freshwater forms are the Charophyta , a division of green algae which includes , for example , Spirogyra and the stoneworts .   No definition of algae is generally accepted . One definition is that algae `` have chlorophyll as their primary photosynthetic pigment and lack a sterile covering of cells around their reproductive cells '' . Some authors exclude all prokaryotes thus do not consider cyanobacteria ( blue-green algae ) as algae .   Algae constitute a polyphyletic group since they do not include a common ancestor , and although their plastids seem to have a single origin , from cyanobacteria , they were acquired in different ways . Green algae are examples of algae that have primary chloroplasts derived from endosymbiotic cyanobacteria . Diatoms and brown algae are examples of algae with secondary chloroplasts derived from an endosymbiotic red alga .   Algae exhibit a wide range of reproductive strategies , from simple asexual cell division to complex forms of sexual reproduction .   Algae lack the various structures that characterize land plants , such as the phyllids ( leaf-like structures ) of bryophytes , rhizoids in nonvascular plants , and the roots , leaves , and other organs found in tracheophytes ( vascular plants ) . Most are phototrophic , although some are mixotrophic , deriving energy both from photosynthesis and uptake of organic carbon either by osmotrophy , myzotrophy , or phagotrophy . Some unicellular species of green algae , many golden algae , euglenids , dinoflagellates , and other algae have become heterotrophs ( also called colorless or apochlorotic algae ) , sometimes parasitic , relying entirely on external energy sources and have limited or no photosynthetic apparatus . Some other heterotrophic organisms , such as the apicomplexans , are also derived from cells whose ancestors possessed plastids , but are not traditionally considered as algae . Algae have photosynthetic machinery ultimately derived from cyanobacteria that produce oxygen as a by-product of photosynthesis , unlike other photosynthetic bacteria such as purple and green sulfur bacteria . Fossilized filamentous algae from the Vindhya basin have been dated back to 1.6 to 1.7 billion years ago .


Alpine climate

Alpine climate is the average weather ( climate ) for the regions above the tree line . This climate is also referred to as a mountain climate or highland climate .


Alternative fuel

Alternative fuels , known as non-conventional and advanced fuels , are any materials or substances that can be used as fuels , other than conventional fuels like ; fossil fuels ( petroleum ( oil ) , coal , and natural gas ) , as well as nuclear materials such as uranium and thorium , as well as artificial radioisotope fuels that are made in nuclear reactors .   Some well-known alternative fuels include biodiesel , bioalcohol ( methanol , ethanol , butanol ) , refuse-derived fuel , chemically stored electricity ( batteries and fuel cells ) , hydrogen , non-fossil methane , non-fossil natural gas , vegetable oil , propane and other biomass sources .


Alternative medicine

Alternative medicine -- or fringe medicine -- includes practices claimed to have the healing effects of medicine but which are disproven , unproven , impossible to prove , or are excessively harmful in relation to their effect ; and where the scientific consensus is that the therapy does not , or can not , work because the known laws of nature are violated by its basic claims ; or where it is considered so much worse than conventional treatment that it would be unethical to offer as treatment . Alternative therapies or diagnoses are not part of medicine or science-based healthcare systems . Alternative medicine consists of a wide variety of practices , products , and therapies -- ranging from those that are biologically plausible but not well tested , to those with known harmful and toxic effects . Contrary to popular belief , significant expense is paid to test alternative medicine , including over $ 2.5 billion spent by the United States government . Almost none show any effect beyond that of false treatment . Perceived effects of alternative medicine may be caused by placebo ; decreased effect of functional treatment ( and therefore potentially decreased side effects ) ; and regression toward the mean where improvement that would have occurred anyway is credited to alternative therapies ; or any combination of the above . Alternative treatments are neither the same as experimental medicine , nor traditional medicine -- although the latter , when used today may be considered alternative .   Alternative medicine has grown in popularity and is used by a significant percentage of the population in many countries . While it has extensively rebranded itself : from quackery to complementary or integrative medicine -- it promotes essentially the same practices . Newer proponents often suggest alternative medicine be used together with functional medical treatment , in a belief that it `` complements '' ( improves the effect of , or mitigates the side effects of ) the treatment . There is no evidence showing they do so , and significant drug interactions caused by alternative therapies may instead negatively influence treatments , making them less effective , notably cancer therapy . Despite being illegal to market alternative therapies for cancer treatment in most of the developed world , many cancer patients use them .   Alternative medical diagnoses and treatments are not taught as part of science-based curricula in medical schools , and are not used in any practice where treatment is based on scientific knowledge or proven experience . Alternative therapies are often based on religion , tradition , superstition , belief in supernatural energies , pseudoscience , errors in reasoning , propaganda , fraud , or lies . Regulation and licensing of alternative medicine and health care providers varies between and within countries .   Alternative medicine is criticized for being based on misleading statements , quackery , pseudoscience , antiscience , fraud , or poor scientific methodology . Promoting alternative medicine has been called dangerous and unethical . Testing alternative medicine that has no scientific basis has been called a waste of scarce research resources . Critics state `` there is really no such thing as alternative medicine , just medicine that works and medicine that does n't '' , and the problem with the idea of `` alternative '' treatments in this sense is that the `` underlying logic is magical , childish or downright absurd '' . It has been strongly suggested that the very idea of any alternative treatment that works is paradoxical , as any treatment proven to work is by definition `` medicine '' .


Amazon basin

The Amazon basin is the part of South America drained by the Amazon River and its tributaries . The Amazon drainage basin covers an area of about 7,500,000 km2 , or roughly 40 percent of the South American continent . It is located in the countries of Bolivia , Brazil , Colombia , Ecuador , Guyana , Peru , Suriname and Venezuela .   Most of the basin is covered by the Amazon Rainforest , also known as Amazonia . With a 5500000 km2 area of dense tropical forest , this is the largest rainforest in the world .


Amazon rainforest

The Amazon rainforest ( Portuguese : Floresta Amazônica or Amazônia ; Selva Amazónica , Amazonía or usually Amazonia ; Forêt amazonienne Amazoneregenwoud ) , also known in English as Amazonia or the Amazon Jungle , is a moist broadleaf forest in the Amazon biome that covers most of the Amazon basin of South America . This basin encompasses 7,000,000 km2 , of which 5,500,000 km2 are covered by the rainforest . This region includes territory belonging to nine nations . The majority of the forest is contained within Brazil , with 60 % of the rainforest , followed by Peru with 13 % , Colombia with 10 % , and with minor amounts in Venezuela , Ecuador , Bolivia , Guyana , Suriname and French Guiana . States or departments in four nations contain `` Amazonas '' in their names . The Amazon represents over half of the planet 's remaining rainforests , and comprises the largest and most biodiverse tract of tropical rainforest in the world , with an estimated 390 billion individual trees divided into 16,000 species .


American Civil War

The American Civil War was fought in the United States from 1861 to 1865 . After a long standing controversy over slavery and state 's rights , war broke out in April 1861 , when Confederates attacked Fort Sumter in South Carolina , shortly after Abraham Lincoln was elected . The nationalists of the Union proclaimed loyalty to the U.S. Constitution . They faced secessionists of the Confederate States of America advocating states ' rights to perpetual slavery and its expansion in the Americas .   Among the 34 U.S. states in February 1861 , seven Southern slave states individually declared their secession from the U.S. to form the Confederate States of America . The Confederacy grew to include eleven states ; it claimed two more border states ( Kentucky and Missouri ) , the Indian Territory , and the southern portions of the Union 's western territories of Arizona and New Mexico , which was organized and incorporated into the Confederacy as Confederate Arizona . The Confederacy was never diplomatically recognized by the United States government , nor was it recognized by any foreign country ( although Britain and France granted it belligerent status ) . The states that remained loyal , including the border states where slavery was legal , were known as the Union or the North .   The North and South quickly raised volunteer and conscription armies that fought mostly in the South over four years . During this time many innovations in warfare occurred , including the development and use of iron-clad ships , ultimately changing naval strategy around the world . The Union finally won the war when General Robert E. Lee surrendered to General Ulysses S. Grant at the battle of Appomattox , which triggered a series of surrenders by Confederate generals throughout the southern states . Four years of intense combat left 620,000 to 750,000 soldiers dead , a higher number than the number of American military deaths in World War I and World War II combined , and much of the South 's infrastructure was destroyed . The Confederacy collapsed , slavery was abolished and 4 million slaves were freed . The Reconstruction Era ( 1863 -- 1877 ) overlapped and followed the war , with the process of restoring national unity , strengthening the national government , and granting civil rights to freed slaves throughout the country . The Civil War is arguably the most studied and written about episode in American history .


American Legislative Exchange Council

The American Legislative Exchange Council ( ALEC ) is a nonprofit organization of conservative state legislators and private sector representatives that drafts and shares model state-level legislation for distribution among state governments in the United States .   ALEC provides a forum for state legislators and private sector members to collaborate on model bills -- draft legislation that members may customize and introduce for debate in their own state legislatures . ALEC has produced model bills on a broad range of issues , such as reducing regulation and individual and corporate taxation , combating illegal immigration , loosening environmental regulations , tightening voter identification rules , weakening labor unions and opposing gun control . Some of these bills dominate legislative agendas in states such as Arizona , Wisconsin , Colorado , Michigan , New Hampshire , and Maine . Approximately 200 model bills become law each year . ALEC also serves as a networking tool among state legislators , allowing them to research conservative policies implemented in other states . Many ALEC legislators say the organization converts campaign rhetoric and nascent policy ideas into legislative language .   ALEC 's activities , while legal , received public scrutiny after being reported by liberal groups in 2011 and after news reports from outlets such as The New York Times and Bloomberg Businessweek described ALEC as an organization that gave corporate interests outsized influence . Resulting public pressure led to a number of legislators and corporations withdrawing from the organization .


Americans

Americans are citizens of the United States of America . The country is home to people of many different national origins . As a result , Americans do not equate their nationality with ethnicity , but with citizenship and allegiance . Although citizens make up the majority of Americans , non-citizen residents , dual citizens , and expatriates may also claim an American identity .   The use in English of the term `` American '' to exclusively mean people of the United States developed from its original use to differentiate English people of the American colonies from English people of England despite its linguistic ambiguity in other senses of the word `` American '' , which can also refer to people from the Americas in general . See Names for United States citizens .


Amundsen–Scott South Pole Station

The Amundsen -- Scott South Pole Station is a United States scientific research station at the South Pole , the southernmost place on the Earth . The station is located on the high plateau of Antarctica at an elevation of 2,835 metres ( 9,301 feet ) above sea level and is administered by the Division of Polar Programs within the National Science Foundation under the United States Antarctic Program ( USAP ) .   The original Amundsen -- Scott Station was built by Navy Seabees for the Federal government of the United States during November 1956 , as a part of its commitment to the scientific goals of the International Geophysical Year ( IGY ) , an international effort lasting from January 1957 through June 1958 , to study , among other things , the geophysics of the polar regions of Earth .   Before November 1956 , there was no permanent human structure at the South Pole , and very little human presence in the interior of Antarctica at all . The few scientific stations in Antarctica were located on and near its seacoast . The station has been continuously occupied since it was built . The Amundsen -- Scott Station has been rebuilt , demolished , expanded , and upgraded several times since 1956 .   Since the Amundsen -- Scott Station is located at the South Pole , it is at the only place on the land surface of the Earth where the Sun is continuously up for six months and then continuously down for six months . ( The only other such place is at the North Pole , on the sea ice in the middle of the Arctic Ocean . ) Thus , during each year , this station experiences one extremely long `` day '' and one extremely long `` night '' . During the six-month `` day '' , the angle of elevation of the Sun above the horizon varies continuously . The Sun rises on the September equinox , reaches its maximum angle above the horizon on the summer solstice in the Southern Hemisphere , around December 20 , and sets on the March equinox .   During the six-month `` night '' , it gets extremely cold at the South Pole , with air temperatures sometimes dropping below -73 ° C . This is also the time of the year when blizzards , sometimes with gale-force winds , strike the Amundsen -- Scott Station . The continuous period of darkness and dry atmosphere make the station an excellent place from which to make astronomical observations , although the Moon is up for two weeks of every 27.3 days .   The number of scientific researchers and members of the support staff housed at the Amundsen -- Scott Station has always varied seasonally , with a peak population of about 200 in the summer operational season from October to February . In recent years the winter-time population has been around 50 people .


An Inconvenient Truth

An Inconvenient Truth is a 2006 American documentary film directed by Davis Guggenheim about former United States Vice President Al Gore 's campaign to educate citizens about global warming via a comprehensive slide show that , by his own estimate made in the film , he has given more than a thousand times . The idea to document his efforts came from producer Laurie David , who saw his presentation at a town-hall meeting on global warming , which coincided with the opening of The Day After Tomorrow . Laurie David was so inspired by Gore 's slide show that she , with producer Lawrence Bender , met with Guggenheim to adapt the presentation into a film .   Premiering at the 2006 Sundance Film Festival and opening in New York City and Los Angeles on May 24 , 2006 , the documentary was a critical and box office success , winning two Academy Awards for Best Documentary Feature and Best Original Song . The film grossed $ 24 million in the U.S. and $ 26 million at the international box office , becoming the tenth highest grossing documentary film to date in the United States . Since the film 's release , An Inconvenient Truth has been credited for raising international public awareness of global warming and reenergizing the environmental movement . The documentary has also been included in science curricula in schools around the world , which has spurred some controversy . A sequel to the film , titled An Inconvenient Sequel : Truth to Power , will be released on July 28 , 2017 .


Anaerobic digestion

Anaerobic digestion is a collection of processes by which microorganisms break down biodegradable material in the absence of oxygen . The process is used for industrial or domestic purposes to manage waste or to produce fuels . Much of the fermentation used industrially to produce food and drink products , as well as home fermentation , uses anaerobic digestion .   Anaerobic digestion occurs naturally in some soils and in lake and oceanic basin sediments , where it is usually referred to as `` anaerobic activity '' . This is the source of marsh gas methane as discovered by Volta in 1776 .   The digestion process begins with bacterial hydrolysis of the input materials . Insoluble organic polymers , such as carbohydrates , are broken down to soluble derivatives that become available for other bacteria . Acidogenic bacteria then convert the sugars and amino acids into carbon dioxide , hydrogen , ammonia , and organic acids . These bacteria convert these resulting organic acids into acetic acid , along with additional ammonia , hydrogen , and carbon dioxide . Finally , methanogens convert these products to methane and carbon dioxide . The methanogenic archaea populations play an indispensable role in anaerobic wastewater treatments .   Anaerobic digestion is used as part of the process to treat biodegradable waste and sewage sludge . As part of an integrated waste management system , anaerobic digestion reduces the emission of landfill gas into the atmosphere . Anaerobic digesters can also be fed with purpose-grown energy crops , such as maize .   Anaerobic digestion is widely used as a source of renewable energy . The process produces a biogas , consisting of methane , carbon dioxide and traces of other ` contaminant ' gases . This biogas can be used directly as fuel , in combined heat and power gas engines or upgraded to natural gas-quality biomethane . The nutrient-rich digestate also produced can be used as fertilizer .   With the re-use of waste as a resource and new technological approaches that have lowered capital costs , anaerobic digestion has in recent years received increased attention among governments in a number of countries , among these the United Kingdom ( 2011 ) , Germany and Denmark ( 2011 ) .


Anders Jonas Ångström

Anders Jonas Ångström ( -LSB- ˈan.ˈdəʂ ˈjuː.ˈnas ˈɔŋ.ˈstrøm -RSB- ; 13 August 181421 June 1874 ) was a Swedish physicist and one of the founders of the science of spectroscopy .


Anglo-Saxon settlement of Britain

The Anglo-Saxon settlement of Britain describes the process which changed the language and culture of most of what became England from Romano-British to Germanic . The Germanic-speakers in Britain , themselves of diverse origins , eventually developed a common cultural identity as Anglo-Saxons . This process occurred from the mid 5th to early 7th centuries , following the end of Roman power in Britain around the year 410 . The settlement was followed by the establishment of Anglo-Saxon kingdoms in the south and east of Britain , later followed by the rest of modern England .   The available evidence includes the scanty contemporary and near-contemporary written record , and archaeological and genetic information . The few literary sources tell of hostility between incomers and natives . They describe violence , destruction , massacre and the flight of the Romano-British population . Also , it has long been supposed that the influence of Celtic languages on Old English was slight . These points have suggested a very large-scale invasion by various Germanic peoples . In this view , held by the majority of historians until the mid to late twentieth century , much of England was cleared of its prior inhabitants . If this ` traditional ' viewpoint were to be correct , the genes of the later English people would have been overwhelmingly inherited from Germanic migrants .   Another view , probably the most widely held today , is that the migrants were relatively few , centred on a warrior elite . They then dominated a process of acculturation to Germanic language and material culture . Consistent with this theory , archaeologists find that settlement patterns and land-use show no clear break with the Romano-British past , though there are marked changes in material culture . This view predicts that the ancestry of the people of Anglo-Saxon and modern England would be largely derived from the native Romano-British . The uncertain results of genetic studies tend to support this prediction .   There are also two less well-supported theories , held by a minority of scholars , both originating from population genetics studies . First , Stephen Oppenheimer has argued that Germanic peoples , language and culture existed in eastern regions of Britain , even in pre-Roman times . This idea has been very actively challenged by a number of linguists . Second , that the early settlers may have arrived in considerable numbers but represented a minority relative to the natives . If these incomers established themselves as a social elite , this could have allowed them enhanced reproductive success ( the so-called ` Apartheid Theory ' ) . In this case , the genes of later Anglo-Saxon England could have been largely derived from moderate numbers of Germanic migrants .


Angstrom

The angstrom (, ; ANG-strəm, ANG-strum) or ångström is a metric unit of length equal to 10−10 m; that is, one ten-billionth of a metre, 0.1 nanometre, or 100 picometres. Its symbol is Å, a letter of the Swedish alphabet. The ångström is not a part of the SI system of units, but it can be considered part of the metric system in general. Although deprecated by both the International Bureau of Weights and Measures (BIPM) and the US National Institute of Standards and Technology (NIST), the unit is still often used in the natural sciences and technology to express sizes of atoms, molecules, microscopic biological structures, and lengths of chemical bonds, arrangement of atoms in crystals, wavelengths of electromagnetic radiation, and dimensions of integrated circuit parts. The atomic (covalent) radii of phosphorus, sulfur, and chlorine are about 1 ångström, while that of hydrogen is about 0.5 ångströms. Visible light has wavelengths in the range of 4000–7000 Å.The unit is named after 19th-century Swedish physicist Anders Jonas Ångström (Swedish: [ˈɔ̂ŋːstrœm]). The BIPM and NIST use the spelling ångström, including Swedish letters; but this form is rare in English texts. Some popular US dictionaries list only the spelling angstrom. The symbol should always be "Å", no matter how the unit is spelled. Nonetheless, "A" is often used in less formal contexts or typographically limited media.


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 '' .


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 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 .


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 .


Anthony Watts (blogger)

Willard Anthony Watts ( born 1958 ) is an American blogger who runs Watts Up With That ? , a popular climate change denial blog that opposes the scientific consensus on climate change . A former television meteorologist and current radio meteorologist , he is also founder of the Surface Stations project , a volunteer initiative to document the condition of U.S. weather stations . The Heartland Institute helped fund some of Watts ' projects , including publishing a report on the Surface Stations project , and has invited him to be a paid speaker at the International Conference on Climate Change from 2008 to 2014 .


Anthozoa

Anthozoa is a class within the phylum Cnidaria . Unlike other cnidarians , anthozoans do not have a medusa stage in their development . Instead , they release sperm and eggs that form a planula , which attaches to some substrate on which the cnidarian grows . Some anthozoans can also reproduce asexually through budding . More than 6,100 species have been described .   The name comes from the Greek words -LSB- : wikt : άνθος , άνθος -RSB- ( ánthos ; `` flower '' ) and -LSB- : wikt : ζῷον , ζώα -RSB- ( zóa ; `` animals '' ) , hence ανθόζωα ( anthozoa ) = `` flower animals '' , a reference to the floral appearance of their perennial polyp stage .


Anti-submarine warfare

Anti-submarine warfare ( ASW , or in older form A/S ) is a branch of underwater warfare that uses surface warships , aircraft , or other submarines to find , track and deter , damage or destroy enemy submarines .   Successful anti-submarine warfare depends on a mix of sensor and weapon technology , training , and experience . Sophisticated sonar equipment for first detecting , then classifying , locating and tracking the target submarine is a key element of ASW . To destroy submarines both the torpedo and mine are used , launched from air , surface and underwater platforms . Other means of destruction have been used in the past but are now obsolete . ASW also involves protecting friendly ships .


Apocalyptic and post-apocalyptic fiction is a subgenre of science fiction , science fantasy or horror fiction literature in which the Earth 's technological civilization is collapsing or has collapsed . The apocalypse event may be climatic , such as runaway climate change ; natural , such as an impact event ; man-made , such as nuclear warfare ; medical , such as a plague or virus , whether natural or man-made ; or imaginative , such as zombie apocalypse or alien invasion . The story may involve attempts to prevent an apocalypse event , deal with the impact and consequences of the event itself , or it may be post-apocalyptic , set after the event . The time frame may be immediately after the catastrophe , focusing on the travails or psychology of survivors , the way to maintain the human race alive and together as one , or considerably later , often including the theme that the existence of pre-catastrophe civilization has been forgotten ( or mythologized ) . Post-apocalyptic stories often take place in a non-technological future world , or a world where only scattered elements of society and technology remain .   Various ancient societies , including the Babylonian and Judaic , produced apocalyptic literature and mythology which dealt with the end of the world and of human society , such as the Epic of Gilgamesh , written ca. 2000 -- 1500 BC . And recognizable modern apocalyptic novels had existed since at least the first quarter of the 19th century , when Mary Shelley 's The Last Man ( 1826 ) was published . However , this form of literature gained widespread popularity after World War II , when the possibility of global annihilation by nuclear weapons entered the public consciousness .   As shown above , the apocalypse is also depicted in visual art , for example in Albert Goodwin 's painting Apocalypse ( 1903 ) .


Apple Corps

Apple Corps Ltd ( informally known as Apple ) is a multi-armed multimedia corporation founded in London in January 1968 by the members of the Beatles to replace their earlier company ( Beatles Ltd ) and to form a conglomerate . Its name ( pronounced `` apple core '' ) is a pun . Its chief division is Apple Records , which was launched in the same year . Other divisions included Apple Electronics , Apple Films , Apple Publishing and Apple Retail , whose most notable venture was the ill-fated Apple Boutique , on the corner of Baker Street and Paddington Street in central London . Apple 's headquarters in the late 1960s was at the upper floors of 94 Baker Street , after that at 95 Wigmore Street , and subsequently at 3 Savile Row . The latter address was also known as the Apple Building , which was home to the Apple Studio .   From 1970 to 2007 , Apple 's chief executive was former Beatles road manager Neil Aspinall , although he did not officially bear that title until Allen Klein had left the company . The current CEO is Jeff Jones . In 2010 , Apple Corps ranked number 2 on the Fast Company magazine 's list of the world 's most innovative companies in the music industry , thanks to the release of The Beatles : Rock Band video game and the remastering of the Beatles ' catalogue .


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 ) .


Arab Spring

The Arab Spring ( الربيع العربي ar-Rabīʻ al-ʻArabī ) also referred to as Arab revolutions ( الثورات العربية aṯ - ` awrāt al-ʻarabiyyah ) or Democracy Spring ( الربيع الديمقراطي ar-Rabīʻ ad-Dīmuqrāṭī ) was a revolutionary wave of both violent and non-violent demonstrations , protests , riots , coups and civil wars in North Africa and the Middle East that began on 17 December 2010 in Tunisia with the Tunisian Revolution .   The Tunisian Revolution effect spread strongly to five other countries : Libya , Egypt , Yemen , Syria and Iraq , where either the regime was toppled or major uprisings and social violence occurred , including civil wars or insurgencies .   Sustained street demonstrations took place in Morocco , Bahrain , Algeria , Iran , Lebanon , Jordan , Kuwait , Oman and Sudan . Minor protests occurred in Djibouti , Mauritania , the Palestinian territories , Saudi Arabia , Somalia and the Moroccan-controlled Western Sahara . A major slogan of the demonstrators in the Arab world is ash-shaʻb yurīd isqāṭ an-niẓām ( `` the people want to bring down the regime '' ) .   The wave of initial revolutions and protests faded by mid-2012 , as many Arab Spring demonstrations were met with violent responses from authorities , as well as from pro-government militias and counter-demonstrators . These attacks were answered with violence from protestors in some cases .  Large-scale conflicts resulted -- the Syrian Civil War , Iraqi insurgency and the following civil war , the Egyptian Crisis and coup , the Libyan Crisis , and the Crisis in Yemen .   A power struggle continued after the immediate response to the Arab Spring . While leadership changed and regimes were held accountable , power went up for grabs across the Arab world . Ultimately it came down to a contentious battle between a consolidation of power by religious elites and the growing support for democracy in many Muslim-majority states . The early hopes that these popular movements would end corruption , increase political participation , and bring about greater economic equity , quickly collapsed in the wake of the counterrevolutionary moves of the deep state in Egypt , the regional and international interventions in Bahrain and Yemen , and the destructive civil wars in Syria and Libya .   Some have referred to the succeeding and still ongoing conflicts as the Arab Winter . As of July 2016 , only the uprising in Tunisia resulted in a transition to constitutional democratic governance .


Aralam Wildlife Sanctuary

Aralam Wildlife Sanctuary is the northernmost wildlife sanctuary of Kerala , southwest India . It is 55 km2 in area and located on the western slope of the Western Ghats . It was established in 1984 . The headquarters of the sanctuary is near Iritty . Aralam Wildlife Sanctuary is situated in the southeast part of Kannur District . It lies between 11 ° 54 ′ and 11 ° 59 ′ north latitude and 75 ° 47 ′ and 75 ° 57 ′ east longitude .   The sanctuary area falls in Aralam , Kelakam and Kottiyoor revenue villages and is located in the northwest slopes of Western Ghats contiguous with the forests of Coorg ( Kodagu ) district of Karnataka state .   The PA ( protected area ) consists of Aralam Range , the only range of Aralam wildlife division , which is part of Northern Wildlife Circle ( Northern Region ) Palakkad . The extent of the sanctuary is 55 km2 . The sanctuary was constituted in 1984 as per GO ( P ) 300/84/AD dated 15 October 1984 .   It was formed by carving out areas from the Odanthode Malavaram of Thalassery special division which was an erstwhile private forest , subsequently taken over by Govt . as per the provisions of the Kerala Private Forests ( vesting and assignment ) Act 1971 and from the Kottiyoor RF of Wayanad Forest Division .   The vested forest portion of the sanctuary is 32.64 km2 and the 22.36 km2 is part of Kottiyoor RF ( Reserved Forest ) .   Till 30.6.98 this sanctuary was a range in Wayanad Wildlife Division . It started functioning as an independent wildlife division since 1.7.98 as per GO ( MS ) 36/98 dated 27.5.98 .   In the First Management Plan the entire area was divided into two zones viz : the Core Zone and the Buffer Zone.Climatic factors include rainfall , temperature , humidity , frost and so on .   Average rainfall : 4000 mm  Temperature : 11.0 ° C to 40.0 ° C  Humidity : 60 to 100 %  Wind : Regular wind during Southwest monsoon  Water source : Cheenkannipuzha


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 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 .


Arctic National Wildlife Refuge

The Arctic National Wildlife Refuge ( ANWR or Arctic Refuge ) is a national wildlife refuge in northeastern Alaska , United States . It consists of 19286722 acre in the Alaska North Slope region . It is the largest National Wildlife Refuge in the country , slightly larger than the Yukon Delta National Wildlife Refuge . The refuge is administered from offices in Fairbanks .   Just across the border in Yukon , Canada , are two Canadian National Parks , Ivvavik and Vuntut .


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 .


Arctic fox

The Arctic fox ( Vulpes lagopus ) , also known as the white fox , polar fox , or snow fox , is a small fox native to the Arctic regions of the Northern Hemisphere and common throughout the Arctic tundra biome . It is well adapted to living in cold environments . It has a deep thick fur which is brown in summer and white in winter . Its body length ranges from 46 to , with a generally rounded body shape to minimize the escape of body heat .   The Arctic fox preys on any small creatures such as : lemmings , voles , ringed seal pups , fish , waterfowl , and seabirds . It also eats carrion , berries , seaweed , insects , and other small invertebrates . Arctic foxes form monogamous pairs during the breeding season and they stay together to raise their young in complex underground dens . Occasionally , other family members may assist in raising their young .


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 .


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 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 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 .


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 .


Argument

In philosophy and logic , an argument is a series of statements typically used to persuade someone of something or to present reasons for accepting a conclusion . The general form of an argument in a natural language is that of premises ( typically in the form of propositions , statements or sentences ) in support of a claim : the conclusion . The structure of some arguments can also be set out in a formal language , and formally defined `` arguments '' can be made independently of natural language arguments , as in math , logic , and computer science .   In a typical deductive argument , the premises guarantee the truth of the conclusion , while in an inductive argument , they are thought to provide reasons supporting the conclusion 's probable truth . The standards for evaluating non-deductive arguments may rest on different or additional criteria than truth , for example , the persuasiveness of so-called `` indispensability claims '' in transcendental arguments , the quality of hypotheses in retroduction , or even the disclosure of new possibilities for thinking and acting .   The standards and criteria used in evaluating arguments and their forms of reasoning are studied in logic . Ways of formulating arguments effectively are studied in rhetoric ( see also : argumentation theory ) . An argument in a formal language shows the logical form of the symbolically represented or natural language arguments obtained by its interpretations .


Art Robinson

Arthur Brouhard Robinson (born March 24, 1942) is an American biochemist, conservative activist, and politician. He was the five-time Republican nominee for the United States House of Representatives for Oregon's 4th congressional district. In 2020 he became Senator-elect of Oregons 2nd Senate District. A former faculty member of the University of California, San Diego, Robinson now runs a privately funded laboratory known as the Oregon Institute of Science and Medicine in Cave Junction, Oregon, a newsletter called Access to Energy, and publishes the Robinson Self-Teaching Home School Curriculum.As the Republican nominee for the Fourth District in Oregon, Robinson ran and lost to Democratic incumbent Peter DeFazio in five consecutive elections: 2010, 2012, 2014, 2016, and 2018. He served as Chairman of the Oregon Republican Party from August 2013 to February 2015.


Arthur D. Levinson

Arthur D. Levinson ( born March 31 , 1950 ) is an American businessman and is the current CEO of Calico ( an Alphabet Inc. venture ) and chairman of Apple Inc. ( 2011 to present ) . He is the former chief executive officer ( 1995 to 2009 ) and chairman ( 1999 to 2014 ) of Genentech .   In addition to serving on the board of Apple Inc. ( 2000 -- present ) , Levinson serves on the board of directors of the Broad Institute ( affiliated with MIT and Harvard ) . Previously , Levinson had served on the board of directors at F. Hoffmann-La Roche ( 2010-2014 ) , NGM Biopharmaceuticals ( 2009-2014 ) , and Amyris Biotechnologies ( 2009-2014 ) . He currently serves on the Board of Scientific Consultants of the Memorial Sloan Kettering Cancer Center , the Industrial Advisory Board of the California Institute for Quantitative Biosciences ( QB3 ) , the Advisory Council for the Princeton University Department of Molecular Biology and the Advisory Council for the Lewis-Sigler Institute for Integrative Genomics .


Artificial intelligence

Artificial intelligence ( AI ) is intelligence exhibited by machines . In computer science , the field of AI research defines itself as the study of `` intelligent agents '' : any device that perceives its environment and takes actions that maximize its chance of success at some goal . Colloquially , the term `` artificial intelligence '' is applied when a machine mimics `` cognitive '' functions that humans associate with other human minds , such as `` learning '' and `` problem solving '' .   As machines become increasingly capable , mental facilities once thought to require intelligence are removed from the definition . For instance , optical character recognition is no longer perceived as an example of `` artificial intelligence '' , having become a routine technology . Capabilities currently classified as AI include successfully understanding human speech , competing at a high level in strategic game systems ( such as chess and Go ) , self-driving cars , intelligent routing in content delivery networks , military simulations , and interpreting complex data .   AI research is divided into subfields that focus on specific problems , approaches , the use of a particular tool , or towards satisfying particular applications .   The central problems ( or goals ) of AI research include reasoning , knowledge , planning , learning , natural language processing ( communication ) , perception and the ability to move and manipulate objects . General intelligence is among the field 's long-term goals . Approaches include statistical methods , computational intelligence , and traditional symbolic AI . Many tools are used in AI , including versions of search and mathematical optimization , logic , methods based on probability and economics . The AI field draws upon computer science , mathematics , psychology , linguistics , philosophy , neuroscience , artificial psychology plus many others .   The field was founded on the claim that human intelligence `` can be so precisely described that a machine can be made to simulate it '' . This raises philosophical arguments about the nature of the mind and the ethics of creating artificial beings endowed with human-like intelligence , issues which have been explored by myth , fiction and philosophy since antiquity . Some people also consider AI a danger to humanity if it progresses unabatedly . Attempts to create artificial intelligence have experienced many setbacks , including the ALPAC report of 1966 , the abandonment of perceptrons in 1970 , the Lighthill Report of 1973 , the second AI winter 1987 -- 1993 and the collapse of the Lisp machine market in 1987 .   In the twenty-first century , AI techniques , both hard ( using a symbolic approach ) and soft ( sub-symbolic ) , have experienced a resurgence following concurrent advances in computer power , sizes of training sets , and theoretical understanding , and AI techniques have become an essential part of the technology industry , helping to solve many challenging problems in computer science . Recent advancements in AI , and specifically in machine learning , have contributed to the growth of Autonomous Things such as drones and self-driving cars , becoming the main driver of innovation in the automotive industry .


Assam

Assam ( -LSB- langpronəˈsæm -RSB- is a state in northeastern India . Located south of the eastern Himalayas , Assam comprises the Brahmaputra Valley and the Barak Valley along with the Karbi Anglong and Dima Hasao districts with an area of 30,285 mi2 . Assam , along with Arunachal Pradesh , Nagaland , Manipur , Mizoram , Tripura , and Meghalaya , is one of the Seven Sister States . Geographically , Assam and these states are connected to the rest of India via a 22 km strip of land in West Bengal called the Siliguri Corridor or `` Chicken 's Neck '' . Assam shares an international border with Bhutan and Bangladesh ; and its culture , people and climate are similar to those of Southeast Asia -- comprising the elements in India 's Look East policy .   Assam is known for Assam tea and Assam silk . The first oil well in Asia was drilled here . The state has conserved the one-horned Indian rhinoceros from near extinction , along with the wild water buffalo , pygmy hog , tiger and various species of Asiatic birds . It provides one of the last wild habitats for the Asian elephant . The Assamese economy is aided by wildlife tourism , centred around Kaziranga National Park and Manas National Park which are World Heritage Sites . Sal tree forests are found in the state which , as a result of abundant rainfall , looks green all year round . Assam receives more rainfall compared to most parts of India . This rain feeds the Brahmaputra River , whose tributaries and oxbow lakes provide the region with a hydro-geomorphic environment .


Association of Chief Police Officers

The Association of Chief Police Officers ( ACPO ) , officially The Association of Chief Police Officers of England , Wales and Northern Ireland , was a not-for-profit private limited company that for many years led the development of policing practices in England , Wales , and Northern Ireland . Established in 1948 , ACPO provided a forum for chief police officers to share ideas and coordinate their strategic operational responses , and advised government in matters such as terrorist attacks and civil emergencies . ACPO coordinated national police operations , major investigations , cross-border policing , and joint law enforcement . ACPO designated Senior Investigative Officers for major investigations and appointed officers to head ACPO units specialising in various areas of policing and crime reduction .   ACPO was led by Chief Constable Sir Hugh Orde , QPM , who was , until 2009 , the Chief Constable of the Police Service of Northern Ireland . He was elected as president by fellow members of ACPO in April 2009 .   ACPO was funded by Home Office grants , profits from commercial activities and contributions from the 44 police authorities in England , Wales , and Northern Ireland .   Following the Parker Review into ACPO , it was replaced in 2015 by a new body , the National Police Chiefs ' Council , set up under a police collaboration agreement under Section 22A of the Police Act 1996 .


Astronomy

Astronomy ( from Greek : αστρονομία ) is a natural science that studies celestial objects and phenomena . It applies mathematics , physics , and chemistry , in an effort to explain the origin of those objects and phenomena and their evolution . Objects of interest include planets , moons , stars , galaxies , and comets ; while the phenomena include supernova explosions , gamma ray bursts , and cosmic microwave background radiation . More generally , all astronomical phenomena that originate outside Earth 's atmosphere are within the purview of astronomy . A related but distinct subject , physical cosmology , is concerned with the study of the Universe as a whole .   Astronomy is the oldest of the natural sciences . The early civilizations in recorded history , such as the Babylonians , Greeks , Indians , Egyptians , Nubians , Iranians , Chinese , and Maya performed methodical observations of the night sky . Historically , astronomy has included disciplines as diverse as astrometry , celestial navigation , observational astronomy and the making of calendars , but professional astronomy is now often considered to be synonymous with astrophysics .   During the 20th century , the field of professional astronomy split into observational and theoretical branches . Observational astronomy is focused on acquiring data from observations of astronomical objects , which is then analyzed using basic principles of physics . Theoretical astronomy is oriented toward the development of computer or analytical models to describe astronomical objects and phenomena . The two fields complement each other , with theoretical astronomy seeking to explain the observational results and observations being used to confirm theoretical results .   Astronomy is one of the few sciences where amateurs can still play an active role , especially in the discovery and observation of transient phenomena . Amateur astronomers have made and contributed to many important astronomical discoveries , such as finding new comets .


Atlanta

Atlanta is the capital of and the most populous city in the U.S. state of Georgia , with an estimated 2016 population of 472,522 . Atlanta is the cultural and economic center of the Atlanta metropolitan area , home to 5,710,795 people and the ninth largest metropolitan area in the United States . Atlanta is the county seat of Fulton County , and a small portion of the city extends eastward into DeKalb County .   In 1837 , Atlanta was founded at the intersection of two railroad lines , and the city rose from the ashes of the American Civil War to become a national center of commerce . In the decades following the Civil Rights Movement , the city earned a reputation as `` too busy to hate '' for the relatively progressive views of its citizens and leaders compared to other cities in the Deep South . Atlanta attained international prominence , and it became the primary transportation hub of the Southeastern United States , via highway , railroad , and air , with Hartsfield -- Jackson Atlanta International Airport being the world 's busiest airport since 1998 .   Atlanta rated an `` alpha - '' world city that exerts a significant impact upon commerce , finance , research , technology , education , media , art , and entertainment . It ranks 40th among world cities and 8th in the nation with a gross domestic product of $ 270 billion . Atlanta 's economy is considered diverse , with dominant sectors that include logistics , professional and business services , media operations , and information technology . Atlanta has topographic features that include rolling hills and dense tree coverage . Revitalization of Atlanta 's neighborhoods , initially spurred by the 1996 Olympics in Atlanta , has intensified in the 21st century , altering the city 's demographics , politics , and culture .


Atlantic Ocean

The Atlantic Ocean is the second largest of the world 's oceans with a total area of about 106,460,000 km2 . It covers approximately 20 percent of the Earth 's surface and about 29 percent of its water surface area . It separates the `` Old World '' from the `` New World '' .   The Atlantic Ocean occupies an elongated , S-shaped basin extending longitudinally between Eurasia and Africa to the east , and the Americas to the west . As one component of the interconnected global ocean , it is connected in the north to the Arctic Ocean , to the Pacific Ocean in the southwest , the Indian Ocean in the southeast , and the Southern Ocean in the south ( other definitions describe the Atlantic as extending southward to Antarctica ) . The Equatorial Counter Current subdivides it into the North Atlantic Ocean and South Atlantic Ocean at about 8 ° N.   Scientific explorations of the Atlantic include the Challenger expedition , the German Meteor expedition , Columbia University 's Lamont-Doherty Earth Observatory and the United States Navy Hydrographic Office .


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 .


Atmosphere of Earth

The atmosphere of Earth is the layer of gases , commonly known as air , that surrounds the planet Earth and is retained by Earth 's gravity . The atmosphere of Earth protects life on Earth by absorbing ultraviolet solar radiation , warming the surface through heat retention ( greenhouse effect ) , and reducing temperature extremes between day and night ( the diurnal temperature variation ) .   By volume , dry air contains 78.09 % nitrogen , 20.95 % oxygen , 0.93 % argon , 0.04 % carbon dioxide , and small amounts of other gases . Air also contains a variable amount of water vapor , on average around 1 % at sea level , and 0.4 % over the entire atmosphere . Air content and atmospheric pressure vary at different layers , and air suitable for use in photosynthesis by terrestrial plants and breathing of terrestrial animals is found only in Earth 's troposphere and in artificial atmospheres .   The atmosphere has a mass of about 5.15 kg , three quarters of which is within about 11 km of the surface . The atmosphere becomes thinner and thinner with increasing altitude , with no definite boundary between the atmosphere and outer space . The Kármán line , at 100 km , or 1.57 % of Earth 's radius , is often used as the border between the atmosphere and outer space . Atmospheric effects become noticeable during atmospheric reentry of spacecraft at an altitude of around 120 km . Several layers can be distinguished in the atmosphere , based on characteristics such as temperature and composition .   The study of Earth 's atmosphere and its processes is called atmospheric science ( aerology ) . Early pioneers in the field include Léon Teisserenc de Bort and Richard Assmann .


Atmosphere of Jupiter

The atmosphere of Jupiter is the largest planetary atmosphere in the Solar System . It is mostly made of molecular hydrogen and helium in roughly solar proportions ; other chemical compounds are present only in small amounts and include methane , ammonia , hydrogen sulfide and water . Although water is thought to reside deep in the atmosphere , its directly measured concentration is very low . The nitrogen , sulfur , and noble gas abundances in Jupiter 's atmosphere exceed solar values by a factor of about three .   The atmosphere of Jupiter lacks a clear lower boundary and gradually transitions into the liquid interior of the planet . From lowest to highest , the atmospheric layers are the troposphere , stratosphere , thermosphere and exosphere . Each layer has characteristic temperature gradients . The lowest layer , the troposphere , has a complicated system of clouds and hazes , comprising layers of ammonia , ammonium hydrosulfide and water . The upper ammonia clouds visible at Jupiter 's surface are organized in a dozen zonal bands parallel to the equator and are bounded by powerful zonal atmospheric flows ( winds ) known as jets . The bands alternate in color : the dark bands are called belts , while light ones are called zones . Zones , which are colder than belts , correspond to upwellings , while belts mark descending air . The zones ' lighter color is believed to result from ammonia ice ; what gives the belts their darker colors is uncertain . The origins of the banded structure and jets are not well understood , though a `` shallow model '' and a `` deep model '' exist .   The Jovian atmosphere shows a wide range of active phenomena , including band instabilities , vortices ( cyclones and anticyclones ) , storms and lightning . The vortices reveal themselves as large red , white or brown spots ( ovals ) . The largest two spots are the Great Red Spot ( GRS ) and Oval BA , which is also red . These two and most of the other large spots are anticyclonic . Smaller anticyclones tend to be white . Vortices are thought to be relatively shallow structures with depths not exceeding several hundred kilometers . Located in the southern hemisphere , the GRS is the largest known vortex in the Solar System . It could engulf two or three Earths and has existed for at least three hundred years . Oval BA , south of GRS , is a red spot a third the size of GRS that formed in 2000 from the merging of three white ovals .   Jupiter has powerful storms , often accompanied by lightning strikes . The storms are a result of moist convection in the atmosphere connected to the evaporation and condensation of water . They are sites of strong upward motion of the air , which leads to the formation of bright and dense clouds . The storms form mainly in belt regions . The lightning strikes on Jupiter are hundreds of times more powerful than those seen on Earth . However , there are so few , that the amount of lightning activity is comparable to Earth .


Atmosphere of Mars

The atmosphere of Mars is the layer of gases surrounding Mars . It is composed mostly of carbon dioxide . The atmospheric pressure on the Martian surface averages 600 Pa , about 0.6 % of Earth 's mean sea level pressure of 101.3 kPa . It ranges from a low of 30 Pa on Olympus Mons 's peak to over 1155 Pa in the depths of Hellas Planitia . This pressure is well below the Armstrong limit for the unprotected human body . Mars 's atmospheric mass of 25 teratonnes compares to Earth 's 5148 teratonnes with a scale height of about 11 km versus Earth 's 7 km .   The Martian atmosphere consists of approximately 96 % carbon dioxide , 1.9 % argon , 1.9 % nitrogen , and traces of free oxygen , carbon monoxide , water and methane , among other gases , for a mean molar mass of 43.34 g/mol . There has been renewed interest in its composition since the detection of traces of methane in 2003 that may indicate life but may also be produced by a geochemical process , volcanic or hydrothermal activity .   The atmosphere is quite dusty , giving the Martian sky a light brown or orange-red color when seen from the surface ; data from the Mars Exploration Rovers indicate suspended particles of roughly 1.5 micrometres in diameter .   On 16 December 2014 , NASA reported detecting an unusual increase , then decrease , in the amounts of methane in the atmosphere of the planet Mars . Organic chemicals have been detected in powder drilled from a rock by the Curiosity rover . Based on deuterium to hydrogen ratio studies , much of the water at Gale Crater on Mars was found to have been lost during ancient times , before the lakebed in the crater was formed ; afterwards , large amounts of water continued to be lost .   On 18 March 2015 , NASA reported the detection of an aurora that is not fully understood and an unexplained dust cloud in the atmosphere of Mars .   On 4 April 2015 , NASA reported studies , based on measurements by the Sample Analysis at Mars ( SAM ) instrument on the Curiosity rover , of the Martian atmosphere using xenon and argon isotopes . Results provided support for a `` vigorous '' loss of atmosphere early in the history of Mars and were consistent with an atmospheric signature found in bits of atmosphere captured in some Martian meteorites found on Earth . This was further supported by results from the MAVEN orbiter circling Mars , that the solar wind is responsible for stripping away the atmosphere of Mars over the years .