Atmosphere of Earth
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Atmosphere of Earth

NASA photo showing Earth's atmosphere at sunset, with Earth silhouetted
Blue light is scattered more than other wavelengths by the gases in the atmosphere, surrounding Earth in a visibly blue layer when seen from space onboard the ISS at an altitude of 335 km (208 mi).[1]
Composition of Earth's atmosphere by volume, excluding water vapor. Lower pie represents trace gases that together compose about 0.043391% of the atmosphere (0.04402961% at April 2019 concentration [2][3]). Numbers are mainly from 2000, with and methane from 2019, and do not represent any single source.[4]

The atmosphere of Earth is the layer of gases, commonly known as air, retained by Earth's gravity, surrounding the planet Earth and forming its planetary atmosphere. The atmosphere of Earth protects life on Earth by creating pressure allowing for liquid water to exist on the Earth's surface, 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.[8] Air also contains a variable amount of water vapor, on average around 1% at sea level, and 0.4% over the entire atmosphere. Air composition, temperature, and atmospheric pressure vary with altitude, 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.

Earth's atmosphere has changed much since its formation as primarily a hydrogen atmosphere, and has changed dramatically on several occasions -- for example, the Great Oxidation Event 2.4 billion years ago, greatly increased oxygen in the atmosphere from practically no oxygen to levels closer to present day. Humans have also contributed to significant changes in atmospheric composition through air pollution, especially since industrialisation, leading to rapid environmental change such as ozone depletion and global warming.


The study of Earth's atmosphere and its processes is called atmospheric science (aerology), and includes multiple subfields, such as climatology and atmospheric physics. Early pioneers in the field include Léon Teisserenc de Bort and Richard Assmann.[10] The study of historic atmosphere is called paleoclimatology.


Mean atmospheric water vapor

The three major constituents of Earth's atmosphere are nitrogen, oxygen, and argon. Water vapor accounts for roughly 0.25% of the atmosphere by mass. The concentration of water vapor (a greenhouse gas) varies significantly from around 10 ppm by volume in the coldest portions of the atmosphere to as much as 5% by volume in hot, humid air masses, and concentrations of other atmospheric gases are typically quoted in terms of dry air (without water vapor).[11] The remaining gases are often referred to as trace gases,[12] among which are the greenhouse gases, principally carbon dioxide, methane, nitrous oxide, and ozone. Besides argon, already mentioned, other noble gases, neon, helium, krypton, and xenon are also present. Filtered air includes trace amounts of many other chemical compounds. Many substances of natural origin may be present in locally and seasonally variable small amounts as aerosols in an unfiltered air sample, including dust of mineral and organic composition, pollen and spores, sea spray, and volcanic ash. Various industrial pollutants also may be present as gases or aerosols, such as chlorine (elemental or in compounds), fluorine compounds and elemental mercury vapor. Sulfur compounds such as hydrogen sulfide and sulfur dioxide (SO2) may be derived from natural sources or from industrial air pollution.

Major constituents of dry air, by volume[8]
Gas Volume(A)
Name Formula in ppmv(B) in %
Nitrogen N2 780,840 78.084
Oxygen O2 209,460 20.946
Argon Ar 9,340 0.9340
Carbon dioxide
(April, 2020)(C)[13]
413.61 0.041361
Neon Ne 18.18 0.001818
Helium He 5.24 0.000524
Methane CH4 1.87 0.000187
Krypton Kr 1.14 0.000114
Not included in above dry atmosphere:
Water vapor(D) H2O 0-30,000(D) 0-3%(E)

    also see volume (thermodynamics)
(B) ppmv: parts per million by volume
(C) The concentration of has been increasing in recent decades
(D) Water vapor is about 0.25% by mass over full atmosphere
(E) Water vapor strongly varies locally[11]

The average molecular weight of dry air, which can be used to calculate densities or to convert between mole fraction and mass fraction, is about 28.946[14] or 28.96[15] g/mol. This is decreased when the air is humid.

The relative concentration of gases remains constant until about 10,000 m (33,000 ft).[16]

The volume fraction of the main constituents of the Earth's atmosphere as a function of height according to the MSIS-E-90 atmospheric model.



In general, air pressure and density decrease with altitude in the atmosphere. However, temperature has a more complicated profile with altitude, and may remain relatively constant or even increase with altitude in some regions (see the temperature section, below). Because the general pattern of the temperature/altitude profile, or lapse rate, is constant and measurable by means of instrumented balloon soundings, the temperature behavior provides a useful metric to distinguish atmospheric layers. In this way, Earth's atmosphere can be divided (called atmospheric stratification) into five main layers. Excluding the exosphere, the atmosphere has four primary layers, which are the troposphere, stratosphere, mesosphere, and thermosphere.[17] From highest to lowest, the five main layers are:

  • Thermosphere: 80 to 700 km (50 to 440 miles)[18]
  • Troposphere: 0 to 12 km (0 to 7 miles)[19]






The thermosphere is the second-highest layer of Earth's atmosphere. It extends from the mesopause (which separates it from the mesosphere) at an altitude of about 80 km (50 mi; 260,000 ft) up to the thermopause at an altitude range of 500-1000 km (310-620 mi; 1,600,000-3,300,000 ft). The height of the thermopause varies considerably due to changes in solar activity.[18] Because the thermopause lies at the lower boundary of the exosphere, it is also referred to as the exobase. The lower part of the thermosphere, from 80 to 550 kilometres (50 to 342 mi) above Earth's surface, contains the ionosphere.

The temperature of the thermosphere gradually increases with height. Unlike the stratosphere beneath it, wherein a temperature inversion is due to the absorption of radiation by ozone, the inversion in the thermosphere occurs due to the extremely low density of its molecules. The temperature of this layer can rise as high as 1500 °C (2700 °F), though the gas molecules are so far apart that its temperature in the usual sense is not very meaningful. The air is so rarefied that an individual molecule (of oxygen, for example) travels an average of 1 kilometre (0.62 mi; 3300 ft) between collisions with other molecules.[20] Although the thermosphere has a high proportion of molecules with high energy, it would not feel hot to a human in direct contact, because its density is too low to conduct a significant amount of energy to or from the skin.

This layer is completely cloudless and free of water vapor. However, non-hydrometeorological phenomena such as the aurora borealis and aurora australis are occasionally seen in the thermosphere. The International Space Station orbits in this layer, between 350 and 420 km (220 and 260 mi).


The mesosphere is the third highest layer of Earth's atmosphere, occupying the region above the stratosphere and below the thermosphere. It extends from the stratopause at an altitude of about 50 km (31 mi; 160,000 ft) to the mesopause at 80-85 km (50-53 mi; 260,000-280,000 ft) above sea level.

Temperatures drop with increasing altitude to the mesopause that marks the top of this middle layer of the atmosphere. It is the coldest place on Earth and has an average temperature around -85 °C (-120 °F; 190 K).[21][22]

Just below the mesopause, the air is so cold that even the very scarce water vapor at this altitude can be sublimated into polar-mesospheric noctilucent clouds. These are the highest clouds in the atmosphere and may be visible to the naked eye if sunlight reflects off them about an hour or two after sunset or a similar length of time before sunrise. They are most readily visible when the Sun is around 4 to 16 degrees below the horizon. Lightning-induced discharges known as transient luminous events (TLEs) occasionally form in the mesosphere above tropospheric thunderclouds. The mesosphere is also the layer where most meteors burn up upon atmospheric entrance. It is too high above Earth to be accessible to jet-powered aircraft and balloons, and too low to permit orbital spacecraft. The mesosphere is mainly accessed by sounding rockets and rocket-powered aircraft.






The troposphere is the lowest layer of Earth's atmosphere. It extends from Earth's surface to an average height of about 12 km (7.5 mi; 39,000 ft), although this altitude varies from about 9 km (5.6 mi; 30,000 ft) at the geographic poles to 17 km (11 mi; 56,000 ft) at the Equator,[19] with some variation due to weather. The troposphere is bounded above by the tropopause, a boundary marked in most places by a temperature inversion (i.e. a layer of relatively warm air above a colder one), and in others by a zone which is isothermal with height.[24][25]

Although variations do occur, the temperature usually declines with increasing altitude in the troposphere because the troposphere is mostly heated through energy transfer from the surface. Thus, the lowest part of the troposphere (i.e. Earth's surface) is typically the warmest section of the troposphere. This promotes vertical mixing (hence, the origin of its name in the Greek word , tropos, meaning "turn"). The troposphere contains roughly 80% of the mass of Earth's atmosphere.[26] The troposphere is denser than all its overlying atmospheric layers because a larger atmospheric weight sits on top of the troposphere and causes it to be most severely compressed. Fifty percent of the total mass of the atmosphere is located in the lower 5.6 km (3.5 mi; 18,000 ft) of the troposphere.


Endeavour orbiting in the thermosphere. Because of the angle of the photo, it appears to straddle the stratosphere and mesosphere that actually lie more than 250 km (160 mi) below. The orange layer is the troposphere, which gives way to the whitish stratosphere and then the blue mesosphere.[27]

Other layers

Within the five principal layers above, that are largely determined by temperature, several secondary layers may be distinguished by other properties:

  • 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 15-35 km (9.3-21.7 mi; 49,000-115,000 ft), though the thickness varies seasonally and geographically. About 90% of the ozone in Earth's atmosphere is contained in the stratosphere.
  • The homosphere and heterosphere are defined by whether the atmospheric gases are well mixed. The surface-based homosphere includes the troposphere, stratosphere, mesosphere, and the lowest part of the thermosphere, where the chemical composition of the atmosphere does not depend on molecular weight because the gases are mixed by turbulence.[28] This relatively homogeneous layer ends at the turbopause found at about 100 km (62 mi; 330,000 ft), the very edge of space itself as accepted by the FAI, which places it about 20 km (12 mi; 66,000 ft) above the mesopause.
  • The planetary boundary layer is the part of the troposphere that is closest to Earth's surface and is directly affected by it, mainly through turbulent diffusion. During the day the planetary boundary layer usually is well-mixed, whereas 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 metres (330 ft) on clear, calm nights to 3,000 m (9,800 ft) or more during the afternoon in dry regions.

The average temperature of the atmosphere at Earth's surface is 14 °C (57 °F; 287 K)[29] or 15 °C (59 °F; 288 K),[30] depending on the reference.[31][32][33]

Physical properties


Pressure and thickness


If the entire mass of the atmosphere had a uniform density equal to sea level density (about 1.2 kg per m3) from sea level upwards, it would terminate abruptly at an altitude of 8.50 km (27,900 ft). It actually decreases exponentially with altitude, dropping by half every 5.6 km (18,000 ft) or by a factor of 1/e every 7.64 km (25,100 ft), the average scale height of the atmosphere below 70 km (43 mi; 230,000 ft). However, the atmosphere is more accurately modeled with a customized equation for each layer that takes gradients of temperature, molecular composition, solar radiation and gravity into account.

In summary, the mass of Earth's atmosphere is distributed approximately as follows:[36]

  • 50% is below 5.6 km (18,000 ft).
  • 90% is below 16 km (52,000 ft).

By comparison, the summit of Mt. Everest is at 8,848 m (29,029 ft); commercial airliners typically cruise between 10 and 13 km (33,000 and 43,000 ft) where the thinner air improves fuel economy; weather balloons reach 30.4 km (100,000 ft) and above; and the highest X-15 flight in 1963 reached 108.0 km (354,300 ft).

Even above the Kármán line, significant atmospheric effects such as auroras still occur. Meteors begin to glow in this region, though the larger ones may not burn up until they penetrate more deeply. The various layers of Earth's ionosphere, important to HF radio propagation, begin below 100 km and extend beyond 500 km. By comparison, the International Space Station and Space Shuttle typically orbit at 350-400 km, within the F-layer of the ionosphere where they encounter enough atmospheric drag to require reboosts every few months. Depending on solar activity, satellites can experience noticeable atmospheric drag at altitudes as high as 700-800 km.

Temperature and speed of sound

Temperature trends in two thick layers of the atmosphere as measured between January 1979 and December 2005 by Microwave Sounding Units and Advanced Microwave Sounding Units on NOAA weather satellites. The instruments record microwaves emitted from oxygen molecules in the atmosphere. Source:[37]



Density and mass


The density of air at sea level is about 1.2 kg/m3 (1.2 g/L, 0.0012 g/cm3). 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.

The average mass of the atmosphere is about 5 quadrillion (5×1015) tonnes 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 5.1480×1018 kg with an annual range due to water vapor of 1.2 or 1.5×1015 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 1.27×1016 kg and the dry air mass as 5.1352 ±0.0003×1018 kg."

Optical properties

Solar radiation (or sunlight) is the energy Earth receives from the Sun. 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. In May 2017, glints of light, seen as twinkling from an orbiting satellite a million miles away, were found to be reflected light from ice crystals in the atmosphere.[38][39]











Refractive index

Distortive effect of atmospheric refraction upon the shape of the sun at the horizon.


The refractive index of air depends on temperature,[40] giving rise to refraction effects when the temperature gradient is large. An example of such effects is the mirage.


An idealised view of three pairs of large circulation cells.


Evolution of Earth's atmosphere

Earliest atmosphere

The first atmosphere consisted of gases in the solar nebula, primarily hydrogen. There were probably simple hydrides such as those now found in the gas giants (Jupiter and Saturn), notably water vapor, methane and ammonia.[41]

Second atmosphere

Outgassing from volcanism, supplemented by gases produced during the late heavy bombardment of Earth by huge asteroids, produced the next atmosphere, consisting largely of nitrogen plus carbon dioxide and inert gases.[41] A major part of carbon-dioxide emissions dissolved in water and reacted with metals such as calcium and magnesium during weathering of crustal rocks to form carbonates that were deposited as sediments. Water-related sediments have been found that date from as early as 3.8 billion years ago.[42]

About 3.4 billion years ago, nitrogen formed the major part of the then stable "second atmosphere". The influence of life has to be taken into account rather soon in the history of the atmosphere, because hints of early life-forms appear as early as 3.5 billion years ago.[43] How Earth at that time maintained a climate warm enough for liquid water and life, if the early Sun put out 30% lower solar radiance than today, is a puzzle known as the "faint young Sun paradox".

The geological record however shows a continuous relatively warm surface during the complete early temperature record of Earth - with the exception of one cold glacial phase about 2.4 billion years ago. In the late Archean Eon an oxygen-containing atmosphere began to develop, apparently produced by photosynthesizing cyanobacteria (see Great Oxygenation Event), which have been found as stromatolite fossils from 2.7 billion years ago. The early basic carbon isotopy (isotope ratio proportions) strongly suggests conditions similar to the current, and that the fundamental features of the carbon cycle became established as early as 4 billion years ago.

Ancient sediments in the Gabon dating from between about 2.15 and 2.08 billion years ago provide a record of Earth's dynamic oxygenation evolution. These fluctuations in oxygenation were likely driven by the Lomagundi carbon isotope excursion.[44]

Third atmosphere

Oxygen content of the atmosphere over the last billion years[45][46]


Before this time, any oxygen produced by photosynthesis was consumed by oxidation of reduced materials, notably iron. Molecules of free oxygen did not start to accumulate in the atmosphere until the rate of production of oxygen began to exceed the availability of reducing materials that removed oxygen. This point signifies a shift from a reducing atmosphere to an oxidizing atmosphere. O2 showed major variations until reaching a steady state of more than 15% by the end of the Precambrian.[47] The following time span from 541 million years ago to the present day is the Phanerozoic Eon, during the earliest period of which, the Cambrian, oxygen-requiring metazoan life forms began to appear.

The amount of oxygen in the atmosphere has fluctuated over the last 600 million years, reaching a peak of about 30% around 280 million years ago, significantly higher than today's 21%. Two main processes govern changes in the atmosphere: Plants using carbon dioxide from the atmosphere and releasing oxygen, and then plants using some oxygen at night by the process of photorespiration with the remainder of the oxygen being used to breakdown adjacent organic material. Breakdown of pyrite and volcanic eruptions release sulfur into the atmosphere, which oxidizes and hence reduces the amount of oxygen in the atmosphere. However, volcanic eruptions also release carbon dioxide, which plants can convert to oxygen. The exact cause of the variation of the amount of oxygen in the atmosphere is not known. Periods with much oxygen in the atmosphere are associated with rapid development of animals. Today's atmosphere contains 21% oxygen, which is great enough for this rapid development of animals.[48]

Air pollution

Air pollution is the introduction into the atmosphere of chemicals, particulate matter or biological materials that cause harm or discomfort to organisms.[49]Stratospheric ozone depletion is caused by air pollution, chiefly from chlorofluorocarbons and other ozone-depleting substances.


Animation shows the buildup of tropospheric in the Northern Hemisphere with a maximum around May. The maximum in the vegetation cycle follows in the late summer. Following the peak in vegetation, the drawdown of atmospheric due to photosynthesis is apparent, particularly over the boreal forests.

Images from space

On October 19, 2015, NASA started a website containing daily images of the full sunlit side of Earth on http://epic.gsfc.nasa.gov/. The images are taken from the Deep Space Climate Observatory (DSCOVR) and show Earth as it rotates during a day.[51]

See also


  1. ^ "Gateway to Astonaut Photos of Earth". NASA. Retrieved .
  2. ^ a b "Trends in Atmospheric Carbon Dioxide", Global Greenhouse Gas Reference Network, NOAA, 2019, retrieved
  3. ^ a b "Trends in Atmospheric Methane", Global Greenhouse Gas Reference Network, NOAA, 2019, retrieved
  4. ^ a b Haynes, H. M., ed. (2016-2017), CRC Handbook of Chemistry and Physics (97th ed.), CRC Press, p. 14-3, ISBN 978-1-4987-5428-6, which cites Allen's Astrophysical Quantities but includes only ten of its largest constituents.
  5. ^ Cox, Arthur N., ed. (2000), Allen's Astrophysical Quantities (Fourth ed.), AIP Press, pp. 258-259, ISBN 0-387-98746-0, which rounds N2 and O2 to four significant digits without affecting the total because 0.004% was removed from N2 and added to O2. It includes 20 constituents.
  6. ^ National Aeronautics and Space Administration (1976), U.S. Standard Atmosphere, 1976 (PDF), p. 3
  7. ^ Allen, C. W. (1976), Astrophysical Quantities (Third ed.), Athlone Press, p. 119, ISBN 0-485-11150-0
  8. ^ a b Two recent reliable sources cited here have total atmospheric compositions, including trace molecules, that exceed 100%. They are Allen's Astrophysical Quantities[5] (2000, 100.001241343%) and CRC Handbook of Chemistry and Physics[4] (2016-2017, 100.004667%), which cites Allen's Astrophysical Quantities. Both are used as references in this article. Both exceed 100% because their CO2 values were increased to 345 ppmv, without changing their other constituents to compensate. This is made worse by the April 2019 value, which is 413.32 ppmv.[2] Although minor, the January 2019 value for is 1866.1 ppbv (parts per billion).[3] Two older reliable sources have dry atmospheric compositions, including trace molecules, that total less than 100%: U.S. Standard Atmosphere, 1976[6] (99.9997147%); and Astrophysical Quantities[7] (1976, 99.9999357%).
  10. ^ Vázquez, M.; Hanslmeier, A. (2006). "Historical Introduction". Ultraviolet Radiation in the Solar System. Astrophysics and Space Science Library. 331. Springer Science & Business Media. p. 17. Bibcode:2005ASSL..331.....V. doi:10.1007/1-4020-3730-9_1. ISBN 978-1-4020-3730-6.
  11. ^ a b Wallace, John M. and Peter V. Hobbs. Atmospheric Science: An Introductory Survey Archived 2018-07-28 at the Wayback Machine. Elsevier. Second Edition, 2006. ISBN 978-0-12-732951-2. Chapter 1
  12. ^ "Trace Gases". Ace.mmu.ac.uk. Archived from the original on 9 October 2010. Retrieved .
  13. ^ "Vital signs: Carbon Dioxide". NASA Climate. May 2020. Retrieved 2020.
  14. ^ Detlev Möller: Luft: Chemie, Physik, Biologie, Reinhaltung, Recht. Walter de Gruyter, 2003, ISBN 3-11-016431-0, S. 173. (View in Google Books).
  15. ^ Yunus Çengel. Termodinamica e trasmissione del calore.
  16. ^ "Air Composition". The Engineering ToolBox. Retrieved . The composition of air is unchanged until elevation of approximately 10.000 m
  17. ^ Zell, Holly (2015-03-02). "Earth's Upper Atmosphere". NASA. Retrieved .
  18. ^ a b Randy Russell (2008). "The Thermosphere". Retrieved .
  19. ^ a b "The height of the tropopause". Das.uwyo.edu. Retrieved .
  21. ^ States, Robert J.; Gardner, Chester S. (January 2000). <0066:TSOTMR>2.0.CO;2 "Thermal Structure of the Mesopause Region (80-105 km) at 40°N Latitude. Part I: Seasonal Variations". Journal of the Atmospheric Sciences. 57 (1): 66-77. Bibcode:2000JAtS...57...66S. doi:10.1175/1520-0469(2000)057<0066:TSOTMR>2.0.CO;2.
  22. ^ Joe Buchdahl. "Atmosphere, Climate & Environment Information Programme". Ace.mmu.ac.uk. Archived from the original on 2010-07-01. Retrieved .
  23. ^ Journal of the Atmospheric Sciences (1993). "stratopause". Retrieved .
  24. ^ Barry, R.G.; Chorley, R.J. (1971). Atmosphere, Weather and Climate. London: Menthuen & Co Ltd. p. 65.
  25. ^ Tyson, P.D.; Preston-Whyte, R.A. (2013). The Weather and Climate of Southern Africa (2nd ed.). Oxford: Oxford University Press. p. 4.
  26. ^ "Troposphere". Concise Encyclopedia of Science & Technology. McGraw-Hill. 1984. It contains about four-fifths of the mass of the whole atmosphere.
  27. ^ "ISS022-E-062672 caption". NASA. Retrieved 2012.
  28. ^ "homosphere - AMS Glossary". Amsglossary.allenpress.com. Archived from the original on 14 September 2010. Retrieved .
  29. ^ "Earth's Atmosphere". Archived from the original on 2009-06-14.
  30. ^ "NASA - Earth Fact Sheet". Nssdc.gsfc.nasa.gov. Archived from the original on 30 October 2010. Retrieved .
  31. ^ "Global Surface Temperature Anomalies". Archived from the original on 2009-03-03.
  32. ^ "Earth's Radiation Balance and Oceanic Heat Fluxes". Archived from the original on 2005-03-03.
  33. ^ "Coupled Model Intercomparison Project Control Run" (PDF). Archived from the original (PDF) on 2008-05-28.
  35. ^ Trenberth, Kevin E.; Smith, Lesley (1970-01-01). "The Mass of the Atmosphere: A Constraint on Global Analyses". Journal of Climate. 18 (6): 864. Bibcode:2005JCli...18..864T. doi:10.1175/JCLI-3299.1. S2CID 16754900.
  36. ^ Lutgens, Frederick K. and Edward J. Tarbuck (1995) The Atmosphere, Prentice Hall, 6th ed., pp. 14-17, ISBN 0-13-350612-6
  37. ^ "Atmospheric Temperature Trends, 1979-2005 : Image of the Day". Earthobservatory.nasa.gov. 2000-01-01. Retrieved .
  38. ^ St. Fleur, Nicholas (19 May 2017). "Spotting Mysterious Twinkles on Earth From a Million Miles Away". The New York Times. Retrieved 2017.
  39. ^ Marshak, Alexander; Várnai, Tamás; Kostinski, Alexander (15 May 2017). "Terrestrial glint seen from deep space: oriented ice crystals detected from the Lagrangian point". Geophysical Research Letters. 44 (10): 5197. Bibcode:2017GeoRL..44.5197M. doi:10.1002/2017GL073248.
  40. ^ Edlén, Bengt (1966). "The refractive index of air". Metrologia. 2 (2): 71-80. Bibcode:1966Metro...2...71E. doi:10.1088/0026-1394/2/2/002.
  41. ^ a b Zahnle, K.; Schaefer, L.; Fegley, B. (2010). "Earth's Earliest Atmospheres". Cold Spring Harbor Perspectives in Biology. 2 (10): a004895. doi:10.1101/cshperspect.a004895. PMC 2944365. PMID 20573713.
  42. ^ B. Windley: The Evolving Continents. Wiley Press, New York 1984
  44. ^ Timothy W. Lyons, Christopher T. Reinhard & Noah J. Planavsky (2014). "Atmospheric oxygenation three billion years ago". Nature. 506 (7488): 307-15. Bibcode:2014Natur.506..307L. doi:10.1038/nature13068. PMID 24553238.
  45. ^ Martin, Daniel; McKenna, Helen; Livina, Valerie (2016). "The human physiological impact of global deoxygenation". The Journal of Physiological Sciences. 67 (1): 97-106. doi:10.1007/s12576-016-0501-0. ISSN 1880-6546. PMC 5138252. PMID 27848144.
  46. ^ http://www.nap.edu/openbook/0309100615/gifmid/30.gif
  48. ^ Peter Ward:[1] Out of Thin Air: Dinosaurs, Birds, and Earth's Ancient Atmosphere
  49. ^ Starting from [2] Pollution - Definition from the Merriam-Webster Online Dictionary
  51. ^ Northon, Karen (2015-10-19). "Daily Views of Earth Available on New NASA Website". NASA. Retrieved .

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