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basically the earth is a giant tennis ball with tiny ppl on lyk me and if yu crack it open ther will be icecream nom nom nom yummy also with a side order of chips so just yanar recycle dudes !!!!!! coz innit i know wer yah live ya cunnt!!! em dont mess with me ya mofo suck it lolloipop cum!!!!!! hahahahahahahahahahahaha etc >>>>>>>>>>>>>>>>>>>>>>> shit about the earth that ne one wants to now tbh its a pile of bollocks!!! byeeeee |
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{{redirect|Air}} |
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{{redirect-distinguish|Qualities of air|Air quality}} |
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[[Image:Top of Atmosphere.jpg|thumb|[[Rayleigh scattering|Blue light is scattered more]] than other wavelengths by the gases in the atmosphere, giving the Earth a blue [[Halo (optical phenomenon)|halo]] when seen from space.]] |
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[[Image:Sunset from the ISS.JPG|thumb|Limb view, of the Earth's atmosphere. Colours roughly denote the layers of the atmosphere.]] |
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The '''atmosphere of Earth''' is a layer of [[gases]] surrounding the planet [[Earth]] that is retained by Earth's [[gravity]]. The [[atmosphere]] protects [[organism|life on Earth]] by absorbing [[ultraviolet]] [[solar radiation]], warming the surface through heat retention ([[greenhouse effect]]), and reducing [[temperature]] extremes between [[Daytime (astronomy)|day]] and [[night]] (the [[diurnal temperature variation]]). |
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[[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{{e|18}} kg, three quarters of which is within about {{convert|11|km|mi ft|abbr=on}} 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 {{convert|120|km|mi|abbr=on}} is where atmospheric effects become noticeable during [[atmospheric reentry]] of spacecraft. The [[Kármán line]], at {{convert|100|km|mi|abbr=on}}, also is often regarded as the boundary between atmosphere and outer space. |
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'''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 in the Earth's atmosphere|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 plant]]s and [[terrestrial animal]]s is currently only known to be found in Earth's [[troposphere]] and artificial atmospheres. |
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== Composition == |
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{{Main|Atmospheric chemistry}} |
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[[File:Atmosphere gas proportions.svg|thumb|right|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<sub>2</sub> and methane from 2009) and do not represent any single source.]] |
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[[File:Atmospheric Water Vapor Mean.2005.030.jpg|thumb|right|Mean atmospheric water vapor]] |
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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,<ref>{{cite web|url=http://www.ace.mmu.ac.uk/eae/Atmosphere/Older/Trace_Gases.html |title=Trace Gases |publisher=Ace.mmu.ac.uk |date= |accessdate=2010-10-16}}</ref> among which are the [[greenhouse gas]]es such as water vapor, carbon dioxide, methane, nitrous oxide, and ozone. Filtered air includes trace amounts of many other [[chemical compound]]s. 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 [[pollutant]]s also may be present, such as [[chlorine]] (elementary or in compounds), [[fluorine]] compounds, elemental [[Mercury (element)|mercury]], and [[sulfur]] compounds such as [[sulfur dioxide]] [SO<sub>2</sub>]. |
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{| class="wikitable" |
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|+'''Composition of dry atmosphere, by volume'''<ref>Source for figures: Carbon dioxide, [http://www.esrl.noaa.gov/gmd/ccgg/trends/#mlo NOAA Earth System Research Laboratory], (updated 2010.06). Methane, [[Intergovernmental Panel on Climate Change|IPCC]] [http://www.grida.no/climate/ipcc_tar/wg1/221.htm#tab61 TAR table 6.1], (updated to 1998). The NASA total was 17 ppmv over 100%, and CO<sub>2</sub> was increased here by 15 ppmv. To normalize, N<sub>2</sub> should be reduced by about 25 ppmv and O<sub>2</sub> by about 7 ppmv.</ref> |
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|colspan=2 style="font-size: 85%" |''ppmv: [[parts per million]] by volume (note: [[volume fraction]] is equal to [[mole fraction]] for ideal gas only, see [[Volume (thermodynamics)#Partial volume|volume (thermodynamics)]])'' |
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! style="text-align:left;"| Gas |
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! style="text-align:left;"|Volume |
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| [[Nitrogen]] (N<sub>2</sub>) || 780,840 ppmv (78.084%) |
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| [[Oxygen]] (O<sub>2</sub>) || 209,460 ppmv (20.946%) |
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| [[Argon]] (Ar) || 9,340 ppmv (0.9340%) |
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| [[Carbon dioxide]] (CO<sub>2</sub>) || 390 ppmv (0.039%) |
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| [[Neon]] (Ne) || 18.18 ppmv (0.001818%) |
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| [[Helium]] (He) || 5.24 ppmv (0.000524%) |
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| [[Methane]] (CH<sub>4</sub>) || 1.79 ppmv (0.000179%) |
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| [[Krypton]] (Kr) || 1.14 ppmv (0.000114%) |
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| [[Hydrogen]] (H<sub>2</sub>) || 0.55 ppmv (0.000055%) |
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| [[Nitrous oxide]] (N<sub>2</sub>O) || 0.3 ppmv (0.00003%) |
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| [[Carbon monoxide]] (CO) || 0.1 ppmv (0.00001%) |
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| [[Xenon]] (Xe) || 0.09 ppmv (9{{e|−6}}%) (0.000009%) |
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| [[Ozone]] (O<sub>3</sub>) || 0.0 to 0.07 ppmv (0 to 7{{e|−6}}%) |
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| [[Nitrogen dioxide]] (NO<sub>2</sub>) || 0.02 ppmv (2{{e|−6}}%) (0.000002%) |
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| [[Iodine]] (I<sub>2</sub>) || 0.01 ppmv (1{{e|−6}}%) (0.000001%) |
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| [[Ammonia]] (NH<sub>3</sub>) || trace |
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|- |
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| Colspan=2 |'''Not included in above dry atmosphere:''' |
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| [[Water vapor]] (H<sub>2</sub>O) || ~0.40% over full atmosphere, typically 1%-4% at surface |
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|} |
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== Structure of the atmosphere == |
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=== Principal layers === |
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[[File:Atmosphere layers-en.svg|thumb|right|upright|Layers of the atmosphere (not to scale)]] |
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In general, air pressure and density decrease in the atmosphere as height increases. However, temperature has a more complicated profile with altitude. Because the general pattern of this profile is constant and recognizable through means such as [[Weather balloon|balloon soundings]], temperature provides a useful metric to distinguish between atmospheric layers. In this way, Earth's atmosphere can be divided into five main layers. From highest to lowest, these layers are: |
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====Exosphere==== |
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{{main|Exosphere}} |
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The outermost layer of Earth's atmosphere extends from the [[exobase]] upward. It is mainly composed of hydrogen and helium. The particles are so far apart that they can travel hundreds of kilometres without colliding with one another. Since the particles rarely collide, the atmosphere no longer behaves like a fluid. These free-moving particles follow ballistic trajectories and may migrate into and out of the [[magnetosphere]] or the [[solar wind]]. |
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====Thermosphere==== |
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{{main|Thermosphere}} |
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Temperature increases with height in the thermosphere from the mesopause up to the [[thermopause]], then is constant with height. Unlike in the stratosphere, where the inversion is caused by absorption of radiation by ozone, in the thermosphere the inversion is a result of the extremely low density of molecules. The temperature of this layer can rise to {{convert|1500|C|abbr=on|sigfig=2}}, though the gas molecules are so far apart that [[kinetic theory|temperature in the usual sense]] is not well defined. The air is so rarefied, that an individual molecule (of [[oxygen]], for example) travels an average of 1 kilometer between collisions with other molecules.<ref>Ahrens, C. Donald. Essentials of Meteorology. Published by Thomson Brooks/Cole, 2005.</ref> The [[International Space Station]] orbits in this layer, between {{convert|320|and|380|km|mi|abbr=on|sigfig=2}}. Because of the relative infrequency of molecular collisions, air above the mesopause is poorly mixed compared to air below. While the composition from the troposphere to the mesosphere is fairly constant, above a certain point, air is poorly mixed and becomes compositionally stratified. The point dividing these two regions is known as the [[turbopause]]. The region below is the homosphere, and the region above is the heterosphere. The top of the thermosphere is the bottom of the exosphere, called the [[exobase]]. Its height varies with solar activity and ranges from about {{convert|350|-|800|km|mi ft|abbr=on|sigfig=2}}. |
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====Mesosphere==== |
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{{main|Mesosphere}} |
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The mesosphere extends from the stratopause to {{convert|80|-|85|km|mi ft|abbr=on|sigfig=2}}. It is the layer where most [[meteor]]s burn up upon entering the atmosphere. Temperature decreases with height in the mesosphere. The [[mesopause]], the temperature minimum that marks the top of the mesosphere, is the coldest place on Earth and has an average temperature around {{convert|-85|C|F K|abbr=on|lk=on|sigfig=2}}.<ref>{{Citation | last = States| first = Robert J.| last2 = Gardner| first2 = Chester S.| title = Thermal Structure of the Mesopause Region (80–105 km) at 40°N Latitude. Part I: Seasonal Variations| journal = Journal of the Atmospheric Sciences 2000| volume = 57| pages = 66–77| year = 2000| month = January| url = http://journals.ametsoc.org/doi/full/10.1175/1520-0469%282000%29057%3C0066%3ATSOTMR%3E2.0.CO%3B2| id = }} |
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</ref> At the [[mesopause]], temperatures may drop to {{convert|-100|C|F K|abbr=on|sigfig=2}}.<ref>http://www.ace.mmu.ac.uk/eae/Atmosphere/Older/Mesosphere.html</ref> Due to the cold temperature of the mesosphere, water vapor is frozen, forming ice clouds (or [[Noctilucent cloud]]s). A type of lightning referred to as either [[Sprite (lightning)|sprites]] or [[ELVES]], form many miles above thunderclouds in the troposphere. |
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====Stratosphere==== |
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{{main|Stratosphere}} |
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The stratosphere extends from the tropopause to about {{convert|51|km|mi ft|abbr=on}}. Temperature increases with height due to increased absorption of [[ultraviolet radiation]] by the [[ozone layer]], which restricts turbulence and mixing. While the temperature may be {{convert|-60|C|F K|abbr=on|sigfig=2}} at the troposphere, the top of the stratosphere is much warmer, and may be near freezing{{Citation needed|date=January 2011}}. The [[stratopause]], which is the boundary between the stratosphere and mesosphere, typically is at {{convert|50|to|55|km|mi ft|abbr=on}}. The pressure here is 1/1000 [[Sea level pressure|sea level]]. |
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====Troposphere==== |
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{{main|Troposphere}} |
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The troposphere begins at the surface and extends to between {{convert|9|km|ft|abbr=on}} at the poles and {{convert|17|km|ft|abbr=on}} at the equator,<ref>http://www-das.uwyo.edu/~geerts/cwx/notes/chap01/tropo.html</ref> with some variation due to weather. The troposphere is mostly heated by transfer of energy from the surface, so on average the lowest part of the troposphere is warmest and temperature decreases with altitude. This promotes vertical mixing (hence the origin of its name in the Greek word "τροπή", ''trope'', meaning turn or overturn). The troposphere contains roughly 80%{{Citation needed|date=November 2009}} of the mass of the atmosphere. The [[tropopause]] is the boundary between the troposphere and stratosphere. |
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=== Other layers === |
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Within the five principal layers determined by temperature are several layers determined by other properties. |
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* The [[ozone layer]] is contained within the stratosphere. In this layer [[ozone]] concentrations are about 2 to 8 parts per million, which is much higher than in the lower atmosphere but still very small compared to the main components of the atmosphere. It is mainly located in the lower portion of the stratosphere from about {{convert|15|-|35|km|mi ft|abbr=on}}, though the thickness varies seasonally and geographically. About 90% of the ozone in our atmosphere is contained in the stratosphere. |
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* The [[ionosphere]], the part of the atmosphere that is ionized by solar radiation, stretches from {{convert|50|to|1000|km|mi ft|abbr=on}} and typically overlaps both the exosphere and the thermosphere. It forms the inner edge of the magnetosphere. It has practical importance because it influences, for example, [[radio]] propagation on the Earth. It is responsible for [[Aurora (astronomy)|aurora]]s. |
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* The homosphere and heterosphere are defined by whether the atmospheric gases are well mixed. In the homosphere the chemical composition of the atmosphere does not depend on molecular weight because the gases are mixed by turbulence.<ref>{{cite web|url=http://amsglossary.allenpress.com/glossary/search?id=homosphere1 |title=''homosphere''—AMS Glossary |publisher=Amsglossary.allenpress.com |date= |accessdate=2010-10-16}}</ref> The homosphere includes the troposphere, stratosphere, and mesosphere. Above the ''[[turbopause]]'' at about {{convert|100|km|mi ft|abbr=on}} (essentially corresponding to the mesopause), the composition varies with altitude. This is because the [[mean free path|distance that particles can move without colliding with one another]] is large compared with the size of motions that cause mixing. This allows the gases to stratify by molecular weight, with the heavier ones such as oxygen and nitrogen present only near the bottom of the heterosphere. The upper part of the heterosphere is composed almost completely of hydrogen, the lightest element. |
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* The [[planetary boundary layer]] is the part of the troposphere that is nearest the Earth's surface and is directly affected by it, mainly through [[turbulence|turbulent diffusion]]. During the day the planetary boundary layer usually is well-mixed, while at night it becomes stably stratified with weak or intermittent mixing. The depth of the planetary boundary layer ranges from as little as about 100 m on clear, calm nights to 3000 m or more during the afternoon in dry regions. |
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The average temperature of the atmosphere at the surface of Earth is {{convert|14|C|F K|abbr=on}}<ref>{{cite web|url=http://www.bambooweb.com/articles/e/a/Earth's_atmosphere.html| title=Earth's Atmosphere| first=|last=}}</ref> or {{convert|15|C|F K|abbr=on}},<ref>{{cite web|url=http://nssdc.gsfc.nasa.gov/planetary/factsheet/earthfact.html |title=NASA - Earth Fact Sheet |publisher=Nssdc.gsfc.nasa.gov |date= |accessdate=2010-10-16}}</ref> depending on the reference.<ref>{{cite web|url=http://www.ncdc.noaa.gov/oa/climate/research/anomalies/index.php| title=Global Surface Temperature Anomalies| first=|last=}}</ref> |
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<ref>{{cite web| url=http://oceanworld.tamu.edu/resources/oceanography-book/radiationbalance.htm| title=Earth's Radiation Balance and Oceanic Heat Fluxes| first=|last=}}</ref><ref>{{cite web| url=http://www-pcmdi.llnl.gov/projects/cmip/overview_ms/control_tseries.pdf |
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| title=Coupled Model Intercomparison Project Control Run| first=|last=}}</ref> |
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== Physical properties == |
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=== Pressure and thickness === |
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{{Main|Atmospheric pressure}} |
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The average atmospheric pressure at [[sea level]] is about 1 atmosphere (atm) = 101.3 kPa (kilopascals) = 14.7 psi (pounds per square inch) = 760 torr = 29.9 inches of mercury (symbol Hg). Total atmospheric mass is 5.1480×10<sup>18</sup> kg (1.135×10<sup>19</sup> lb),<ref>{{cite web|url=http://ams.allenpress.com/perlserv/?request=get-abstract&doi=10.1175%2FJCLI-3299.1 |title=The Mass of the Atmosphere: A Constraint on Global Analyses |publisher=Ams.allenpress.com |date=1970-01-01 |accessdate=2010-10-16}}</ref> about 2.5% less than would be inferred naively from the average sea level pressure and the Earth's area of 51007.2 megahectares, this portion being displaced by the Earth's mountainous terrain. Atmospheric pressure is the total weight of the air above unit area at the point where the pressure is measured. Thus air pressure varies with location and time, because the amount of air above the Earth's surface varies. |
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If atmospheric density were to remain constant with height the atmosphere would terminate abruptly at {{convert|8.50|km|ft|abbr=on}}. Instead, density decreases with height, dropping by 50% at an altitude of about {{convert|5.6|km|ft|abbr=on}}. As a result the pressure decrease is approximately exponential with height, so that pressure decreases by a factor of two approximately every {{convert|5.6|km|ft|abbr=on}} and by a factor of ''e'' = 2.718… approximately every {{convert|7.64|km|ft|abbr=on}}, the latter being the average [[scale height]] of Earth's atmosphere below {{convert|70|km|mi ft|abbr=on}}. However, because of changes in temperature, average molecular weight, and gravity throughout the atmospheric column, the dependence of atmospheric pressure on altitude is modeled by separate equations for each of the layers listed above. Even in the exosphere, the atmosphere is still present. This can be seen by the effects of [[atmospheric drag]] on [[satellite]]s. |
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In summary, the equations of pressure by altitude in the above references can be used directly to estimate atmospheric thickness. However, the following published data are given for reference:<ref>Lutgens, Frederick K. and Edward J. Tarbuck (1995) ''The Atmosphere'', Prentice Hall, 6th ed., pp14-17, ISBN 0-13-350612-6</ref> |
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* 50% of the atmosphere by mass is below an altitude of {{convert|5.6|km|ft|abbr=on}}. |
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* 90% of the atmosphere by mass is below an altitude of {{convert|16|km|ft|abbr=on}}. The common altitude of commercial airliners is about {{convert|10|km|ft|abbr=on}} and Mt. Everest's summit is {{convert|8848|m|ft|abbr=on}} above sea level. |
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* 99.99997% of the atmosphere by mass is below {{convert|100|km|mi ft|abbr=on}}, although in the rarefied region above this there are [[Aurora (astronomy)|aurora]]s and other atmospheric effects. The highest [[North American X-15|X-15]] plane flight in 1963 reached an altitude of {{convert|108.0|km|ft|abbr=on}}. |
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=== Density and mass === |
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[[File:Atmosphere model.png|thumb|Temperature and mass density against altitude from the [[NRLMSISE-00]] [[standard atmosphere]] model (the eight dotted lines in each "decade" are at the eight cubes 8, 27, 64, ..., 729)]] |
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{{Main|Density of air}} |
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The density of air at sea level is about 1.2 kg/m<sup>3</sup> (1.2 g/L). Density is not measured directly but is calculated from measurements of temperature, pressure and humidity using the equation of state for air (a form of the [[ideal gas law]]). Atmospheric density decreases as the altitude increases. This variation can be approximately modeled using the [[barometric formula]]. More sophisticated models are used to predict orbital decay of satellites. |
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The average mass of the atmosphere is about 5 quadrillion (5{{e|15}}) [[tonne]]s or 1/1,200,000 the mass of Earth. According to the American [[National Center for Atmospheric Research]], "The total mean mass of the atmosphere is 5.1480{{E|18}} kg with an annual range due to water vapor of 1.2 or 1.5{{E|15}} kg depending on whether surface pressure or water vapor data are used; somewhat smaller than the previous estimate. The mean mass of water vapor is estimated as 1.27{{E|16}} kg and the dry air mass as 5.1352 ±0.0003{{E|18}} kg." |
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== Optical properties == |
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{{See also|Sunlight}} |
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Solar [[radiation]] (or sunlight) is the energy the Earth receives from the [[Sun]]. The Earth also emits radiation back into space, but at longer wavelengths that we cannot see. Part of the incoming and emitted radiation is absorbed or reflected by the atmosphere. |
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=== Scattering === |
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{{Main|Scattering}} |
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When light passes through our atmosphere, [[photon]]s interact with it through ''scattering''. If the light does not interact with the atmosphere, it is called ''direct radiation'' and is what you see if you were to look directly at the Sun. ''Indirect radiation'' is light that has been scattered in the atmosphere. For example, on an [[overcast]] day when you cannot see your shadow there is no direct radiation reaching you, it has all been scattered. As another example, due to a phenomenon called [[Rayleigh scattering]], shorter (blue) wavelengths scatter more easily than longer (red) wavelengths. This is why the sky looks blue, you are seeing scattered blue light. This is also why [[sunset]]s are red. Because the Sun is close to the horizon, the Sun's rays pass through more atmosphere than normal to reach your eye. Much of the blue light has been scattered out, leaving the red light in a sunset. |
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=== Absorption === |
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{{Main|Absorption (electromagnetic radiation)}} |
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Different molecules absorb different wavelengths of radiation. For example, O<sub>2</sub> and O<sub>3</sub> absorb almost all wavelengths shorter than 300 [[nanometer]]s. Water (H<sub>2</sub>O) absorbs many wavelengths above 700 nm. When a molecule absorbs a photon, it increases the energy of the molecule. We can think of this as heating the atmosphere, but the atmosphere also cools by emitting radiation, as discussed below. |
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[[File:Atmospheric electromagnetic opacity.svg|thumb|left|Rough plot of Earth's atmospheric [[transmittance]] (or opacity) to various wavelengths of electromagnetic radiation, including [[visible light]].]] |
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The combined [[absorption spectra]] of the gases in the atmosphere leave "windows" of low [[Opacity (optics)|opacity]], allowing the transmission of only certain bands of light. The [[optical window]] runs from around 300 nm ([[ultraviolet]]-C) up into the range humans can see, the [[visible spectrum]] (commonly called [[light]]), at roughly 400–700 nm and continues to the [[infrared]] to around 1100 nm. There are also [[Infrared window|infrared]] and [[radio window]]s that transmit some infrared and [[radio waves]] at longer wavelengths. For example, the radio window runs from about one centimeter to about eleven-meter waves. |
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=== Emission === |
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{{Main|Emission (electromagnetic radiation)}} |
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''Emission'' is the opposite of absorption, it is when an object emits radiation. Objects tend to emit amounts and wavelengths of radiation depending on their "[[black body]]" emission curves, therefore hotter objects tend to emit more radiation, with shorter wavelengths. Colder objects emit less radiation, with longer wavelengths. For example, the Sun is approximately {{convert|6000|K|lk=on}}, its radiation peaks near 500 nm, and is visible to the human eye. The Earth is approximately {{convert|290|K|abbr=on}}, so its radiation peaks near 10,000 nm, and is much too long to be visible to humans. |
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Because of its temperature, the atmosphere emits infrared radiation. For example, on clear nights the Earth's surface cools down faster than on [[cloud]]y nights. This is because clouds (H<sub>2</sub>O) are strong absorbers and emitters of infrared radiation. This is also why it becomes colder at night at higher elevations. The atmosphere acts as a "blanket" to limit the amount of radiation the Earth loses into space. |
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The ''greenhouse effect'' is directly related to this absorption and emission (or "blanket") effect. Some chemicals in the atmosphere absorb and emit infrared radiation, but do not interact with sunlight in the visible spectrum. Common examples of these chemicals are CO<sub>2</sub> and H<sub>2</sub>O. If there are too much of these ''greenhouse gases'', sunlight heats the Earth's surface, but the gases block the infrared radiation from exiting back to space. This imbalance causes the Earth to warm, and thus [[climate change]]. |
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=== Refractive index === |
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The [[refractive index]] of air is close to, but just greater than 1. Systematic variations in refractive index can lead to the bending of light rays over long optical paths. One example is that, under some circumstances, observers onboard ships can see other vessels just over the [[horizon]] because light is refracted in the same direction as the [[curvature]] of the Earth's surface. |
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The refractive index of air depends on temperature, giving rise to refraction effects when the temperature gradient is large. An example of such effects is the [[mirage]]. |
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{{See also|Scintillation (astronomy)}} |
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== Circulation == |
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{{Main|Atmospheric circulation}} |
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[[File:AtmosphCirc2.png|thumb|right|An idealised view of three large circulation cells.]] |
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''Atmospheric circulation'' is the large-scale movement of air through the troposphere, and the means (with [[ocean circulation]]) by which [[heat]] is distributed around the Earth. The large-scale structure of the atmospheric circulation varies from year to year, but the basic structure remains fairly constant as it is determined by the Earth's rotation rate and the difference in solar radiation between the equator and poles. |
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== Evolution of Earth's atmosphere == |
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{{See also|History of Earth|Gaia hypothesis|Paleoclimatology}} |
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=== Earliest atmosphere === |
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The outgassings of the Earth was stripped away by solar winds early in the history of the planet until a steady state was established, the first atmosphere. Based on today's volcanic evidence, this atmosphere would have contained 60% hydrogen, 20% oxygen (mostly in the form of water vapor), 10% carbon dioxide, 5 to 7% hydrogen sulfide, and smaller amounts of nitrogen, carbon monoxide, free hydrogen, methane and inert gases.{{Citation needed|date=January 2010}} |
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A major rainfall led to the buildup of a vast ocean, enriching the other agents, first carbon dioxide and later nitrogen and inert gases. A major part of carbon dioxide exhalations were soon dissolved in water and built up carbonate sediments. |
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=== Second atmosphere === |
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Water-related sediments have been found dating from as early as 3.8 billion years ago.<ref>B. Windley: ''The Evolving Continents.'' Wiley Press, New York 1984</ref> About 3.4 billion years ago, nitrogen was the major part of the then stable "second atmosphere". An influence of life has to be taken into account rather soon in the history of the atmosphere, since hints of early life forms are to be found as early as 3.5 billion years ago.<ref>J. Schopf: ''Earth's Earliest Biosphere: Its Origin and Evolution.'' Princeton University Press, Princeton, N.J., 1983</ref> The fact that this is not perfectly in line with the - compared to today 30% lower - solar radiance of the early Sun has been described as the "[[faint young Sun paradox]]". |
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The geological record however shows a continually relatively warm surface during the complete early [[temperature record]] of the Earth with the exception of one cold glacial phase about 2.4 billion years ago. In the late [[Archaean]] eon an oxygen-containing atmosphere began to develop, apparently from photosynthesizing algae which have been found as [[stromatolite]] fossils from 2.7 billion years ago. The early basic carbon [[isotopy]] (isotope ratio proportions) is very much in line with what is found today,<ref name="CCD">Celestial climate driver: a perspective from 4 billion years of the carbon cycle Geoscience Canada, March, 2005 by Jan Veizer</ref> suggesting that the fundamental features of the [[carbon cycle]] were established as early as 4 billion years ago. |
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=== Third atmosphere === |
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[[File:Sauerstoffgehalt-1000mj2.png|thumb|Oxygen content of the atmosphere over the last billion years]] |
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The accretion of continents about 3.5 billion years ago<ref>Veizer in B. F. Windley (ed.), The Early History of the Earth, John Wiley and Sons, London, p. 569., 1976</ref> added [[plate tectonics]], constantly rearranging the continents and also shaping long-term climate evolution by allowing the transfer of carbon dioxide to large land-based carbonate storages. Free oxygen did not exist until about 1.7 billion years ago and this can be seen with the development of the red beds and the end of the banded iron formations. This signifies a shift from a reducing atmosphere to an oxidising atmosphere. O<sub>2</sub> showed major ups and downs until reaching a steady state of more than 15%.<ref>Christopher R. Scotese, [http://www.scotese.com/precamb_chart.htm Back to Earth History : Summary Chart for the Precambrian], Paleomar Project</ref> The following time span was the [[Phanerozoic]] eon, during which oxygen-breathing [[metazoan]] life forms began to appear. |
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Currently, [[anthropogenic]] greenhouse gases are increasing in the atmosphere. According to the [[Intergovernmental Panel on Climate Change]], this increase is the main cause of [[global warming]].<ref name="grida7">{{cite web | url= http://www.ipcc.ch/pdf/assessment-report/ar4/wg1/ar4-wg1-spm.pdf | format=PDF | title=Summary for Policymakers | work=Climate Change 2007: The Physical Science Basis. Contribution of Working Group I to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change | date=5 February 2007 | publisher=[[Intergovernmental Panel on Climate Change]]}}</ref> |
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=== Air pollution === |
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{{Main|Air pollution}} |
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''Air pollution'' is the introduction of [[chemical]]s, [[particulate matter]], or [[biological material]]s that cause harm or discomfort to organisms into the atmosphere.<ref>Starting from [http://www.merriam-webster.com/dictionary/pollution] Pollution - Definition from the Merriam-Webster Online Dictionary</ref> [[Stratosphere|Stratospheric]] [[ozone depletion]] is believed to be caused by air pollution (chiefly from [[chlorofluorocarbons]]).{{Citation needed|date=October 2009}} |
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== See also == |
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{{portal|Atmosphere}} |
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* [[Aerial perspective]] |
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* [[Air glow]] |
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* [[Airshed]] |
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* [[Atmosphere]] (for information on atmospheres in general) |
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* [[Atmospheric dispersion modeling]] |
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* [[Atmospheric electricity]] |
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* [[Atmospheric models]] |
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* [[Atmospheric Radiation Measurement]] (ARM) (in the U.S.) |
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* [[Atmospheric stratification]] |
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* [[Aviation]] |
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* [[Biosphere]] |
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* [[Carbon dioxide in the Earth's atmosphere]] |
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* [[Compressed air]] |
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* [[Global dimming]] |
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* [[Historical temperature record]] |
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* [[Hydrosphere]] |
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* [[Kyoto Protocol]] |
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* [[Lithosphere]] |
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* [[Standard Dry Air]] |
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* [[COSPAR international reference atmosphere]] (CIRA) |
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* [[U.S. Standard Atmosphere]] |
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* [[Warm period]] |
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* [[Water vapor#Water vapor in Earth's atmosphere|Water vapor in Earth's atmosphere]] |
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== References == |
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{{reflist|colwidth=30em}} |
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== External links == |
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{{Commons category|Earth's atmosphere}} |
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* [http://modelweb.gsfc.nasa.gov/spdf_models_home.html#atmo NASA atmosphere models] |
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* [http://nssdc.gsfc.nasa.gov/planetary/factsheet/earthfact.html NASA's Earth Fact Sheet] |
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* [http://atmospheres.agu.org/ American Geophysical Union: Atmospheric Sciences] |
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* [http://www.stuffintheair.com/ Stuff in the Air] Find out what the atmosphere contains. |
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* [http://www.srh.noaa.gov/srh/jetstream/atmos/layers.htm Layers of the Atmosphere] |
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* [http://www.scribd.com/doc/22854/Air-Atmosphere-and-Airplanes/ Answers to several questions of curious kids related to Air and Atmosphere] |
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* [http://amsglossary.allenpress.com/glossary The AMS Glossary of Meteorology] |
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* [http://www.vega.org.uk/video/programme/111 Paul Crutzen Interview] Free video of Paul Crutzen Nobel Laureate for his work on decomposition of ozone talking to Harry Kroto Nobel Laureate by the Vega Science Trust. |
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* [http://des.memphis.edu/lurbano/Geog1010/Fall05/chapter_03/chapter_03.html Slides describing the Earth's modern atmosphere] |
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{{Earthsatmosphere}} |
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Revision as of 13:55, 13 May 2011
basically the earth is a giant tennis ball with tiny ppl on lyk me and if yu crack it open ther will be icecream nom nom nom yummy also with a side order of chips so just yanar recycle dudes !!!!!! coz innit i know wer yah live ya cunnt!!! em dont mess with me ya mofo suck it lolloipop cum!!!!!! hahahahahahahahahahahaha etc >>>>>>>>>>>>>>>>>>>>>>> shit about the earth that ne one wants to now tbh its a pile of bollocks!!! byeeeee