Atmosphere of Earth Article

Atmosphere of Earth Article - Atmosphere of Earth From...

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Atmosphere of Earth From Wikipedia, the free encyclopedia Jump to: navigation , search "Air" redirects here. For other uses, see Air (disambiguation) . It has been suggested that Atmospheric stratification be merged into this article or section. ( Discuss ) Blue light is scattered more than other wavelengths by the gases in the atmosphere, giving the Earth a blue halo when seen from space. L i m b v i e w , o f t h e E a r t
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h ' s a t m o s p h e r e . C o l o u r s r o u g h l y d e n o t e t h e l a y e r s o f
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t h e a t m o s p h e r e . The atmosphere of Earth is a layer of gases surrounding the planet Earth that is retained by Earth's gravity . The atmosphere 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 . Atmospheric stratification describes the structure of the atmosphere, dividing it into distinct layers, each with specific characteristics such as temperature or composition. The atmosphere has a mass of about 5×10 18 kg, three quarters of which is within about 11 km (6.8 mi; 36,000 ft) of the surface. The atmosphere becomes thinner and thinner with increasing altitude, with no definite boundary between the atmosphere and outer space . An altitude of 120 km (75 mi) is where atmospheric effects become noticeable during atmospheric reentry of spacecraft. The Kármán line , at 100 km (62 mi), also is often regarded as the boundary between atmosphere and outer space. Air is the name given to atmosphere used in breathing and photosynthesis . Dry air contains roughly (by volume) 78.09% nitrogen , 20.95% oxygen , 0.93% argon , 0.039% carbon dioxide , and small amounts of other gases. Air also contains a variable amount of water vapor , on average around 1%. While air content and atmospheric pressure varies at different layers, air suitable for the survival of terrestrial plants and terrestrial animals is currently known only to be found in Earth's troposphere and artificial atmospheres. Composition Main article: Atmospheric chemistry
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Composition of Earth's atmosphere. The lower pie represents the trace gases which together compose 0.039% of the atmosphere. Values normalized for illustration. The numbers are from a variety of years (mainly 1987, with CO 2 and methane from 2009) and do not represent any single source. Mean atmospheric water vapor Air is mainly composed of nitrogen, oxygen, and argon, which together constitute the major gases of the atmosphere. The remaining gases are often referred to as trace gases, [1] among which are the greenhouse gases such as water vapor, carbon dioxide, methane, nitrous oxide, and ozone. Filtered air includes trace amounts of many other chemical compounds . Many natural substances may be present in tiny amounts in an unfiltered air sample, including dust , pollen and spores , sea spray , and volcanic ash . Various industrial pollutants also may be present, such as chlorine (elementary or in compounds), fluorine compounds, elemental mercury , and sulfur compounds such as sulfur dioxide [SO 2 ].
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