View source for Stratosphere

{{Other uses}}
{{short description|Layer of the atmosphere above the troposphere}}
[[File:ISS-46 Soyuz TMA-17M reentry.jpg|thumb|upright=1.25|[[Afterglow]] of the [[troposphere]] (orange), the '''stratosphere''' (blue) and the [[mesosphere]] (dark), at which [[atmospheric entry]] of objects begins, as in this case of a [[spacecraft]] reentry that leaves [[contrail]]s.]]

[[File:Atmosphere layers-en.svg|thumb|upright=0.8|Earth's five primary atmospheric layers: [[exosphere]], [[thermosphere]], [[mesosphere]], stratosphere, and [[troposphere]] (not to scale).]]

The '''stratosphere''' is the second-lowest [[atmospheric stratification|layer]] of the [[atmosphere of Earth]], located above the [[troposphere]] and below the [[mesosphere]]. Pronounced {{IPAc-en|ˈ|s|t|r|æ|t|ə|ˌ|s|f|ɪər|,_|-|t|oʊ|-}},<ref>{{cite Dictionary.com|stratosphere}}</ref> the name originates {{etymology|grc|''{{wikt-lang|grc|στρωτός}}'' ({{grc-transl|στρωτός}})|layer, stratum||-[[sphere]]}}.<ref>{{Citation |last=Jones |first=Daniel |author-link=Daniel Jones (phonetician) |title=English Pronouncing Dictionary |editor=Peter Roach |editor2=James Hartmann |editor3=Jane Setter |place=Cambridge |publisher=[[Cambridge University Press]] |orig-year=1917 |year=2003 |isbn=978-3-12-539683-8 }}</ref><ref>{{MerriamWebsterDictionary|Stratosphere}}</ref> The stratosphere is composed of [[stable and unstable stratification|stratified]] [[temperature]] zones, with the warmer layers of [[air]] located higher (closer to [[outer space]]) and the cooler layers lower (closer to the [[planetary surface]] of the Earth). The increase of temperature with [[altitude]] is a result of the absorption of the [[Sun]]'s [[ultraviolet]] (UV) radiation by the [[ozone layer]], where [[ozone]] is [[exothermic]]ally [[photodissociation|photolyze]]d into [[oxygen]] in [[ozone-oxygen cycle|a cyclical fashion]].<ref name=ucarOverview>{{cite web |title=The Stratosphere - overview |url=https://scied.ucar.edu/shortcontent/stratosphere-overview |website=scied.ucar.edu |publisher=University Corporation for Atmospheric Research |access-date=25 July 2018 |language=en}}</ref> This [[inversion (meteorology)|temperature inversion]] is in contrast to the troposphere, where temperature decreases with altitude, and between the troposphere and stratosphere is the [[tropopause]] border that demarcates the beginning of the temperature inversion.

Near the [[equator]], the lower edge of the stratosphere is as high as {{cvt|20|km|sigfig=2|ft mi}}, at mid-latitudes around {{cvt|10|km|sigfig=2|ft mi}}, and at the [[geographical pole|poles]] about {{cvt|7|km|sigfig=2|ft mi}}.<ref name=ucarOverview/> Temperatures range from an average of {{cvt|-51|C|sigfig=2|F K}} near the tropopause to an average of {{cvt|-15|C|sigfig=2|F K}} near the mesosphere.<ref name="nwsJetStream">{{cite web |title=NWS JetStream - Layers of the Atmosphere |url=https://www.weather.gov/jetstream/layers |website=www.weather.gov |language=EN-US}}</ref> Stratospheric temperatures also vary within the stratosphere as the [[season]]s change, reaching particularly low temperatures in the [[polar night]] (winter).<ref name="nasaOzoneWatch">{{cite web |title=Nasa Ozone Watch: Polar vortex facts |url=https://ozonewatch.gsfc.nasa.gov/facts/vortex_NH.html |website=ozonewatch.gsfc.nasa.gov |language=en-us}}</ref> [[Wind]]s in the stratosphere can far exceed those in the troposphere, reaching near {{cvt|60|m/s|km/h mph}} in the Southern [[polar vortex]].<ref name="nasaOzoneWatch"/>

== Discovery ==
In 1902, [[Léon Teisserenc de Bort]] from France and [[Richard Assmann]] from Germany, in separate but coordinated publications and following years of observations, published the discovery of an isothermal layer at around 11–14&nbsp; km (6.8-8.7&nbsp; mi), which is the base of the lower stratosphere. This was based on temperature profiles from mostly unmanned and a few manned instrumented balloons.<ref>{{Citation |last=Steinhagen |first=Hans |title=Der Wettermann - Leben und Werk Richard Aßmanns |place=Neuenhagen, Germany |publisher=Findling |year=2005 |isbn=978-3-933603-33-3 }}</ref>

== Ozone layer ==
{{Further|Ozone layer}}
[[File:Layersofozone 1.jpeg 1240x510 q85 subsampling-2.jpg|thumb|The ozone layer in the stratosphere blocks harmful UV radiation from reaching the surface of the Earth. A gamma-ray burst would deplete the ozone layer, allowing UV radiation through.]]
The mechanism describing the formation of the ozone layer was described by British mathematician and [[geophysicist]] [[Sydney Chapman (mathematician)|Sydney Chapman]] in 1930, and is known as the Chapman cycle or [[ozone–oxygen cycle]].<ref>{{Cite book |last= Jacob |first=Daniel J. |url=http://acmg.seas.harvard.edu/people/faculty/djj/book/bookchap10.html |title=Introduction to Atmospheric Chemistry |date=1999 |publisher=Princeton University Press |isbn=9781400841547 |chapter=CHAPTER 10. STRATOSPHERIC OZONE |access-date=2020-10-20 |archive-url=https://web.archive.org/web/20190930034719/http://acmg.seas.harvard.edu/people/faculty/djj/book/bookchap10.html |archive-date=2019-09-30 |url-status=dead |via=acmg.seas.harvard.edu}}</ref> Molecular oxygen absorbs high energy sunlight in the [[UV-C]] region, at wavelengths shorter than about 240&nbsp;nm. Radicals produced from the homolytically split oxygen molecules combine with molecular oxygen to form ozone. Ozone in turn is [[Photolyzation|photolyzed]] much more rapidly than molecular oxygen as it has a stronger absorption that occurs at longer wavelengths, where the solar emission is more intense. [[Ozone]] (O<sub>3</sub>) photolysis produces O and O<sub>2</sub>. The oxygen atom product combines with atmospheric molecular oxygen to reform O<sub>3</sub>, releasing heat. The rapid photolysis and reformation of ozone heat the stratosphere, resulting in a temperature inversion. This increase of temperature with altitude is characteristic of the stratosphere; its resistance to vertical mixing means that it is stratified. Within the stratosphere temperatures increase with altitude ''(see [[temperature inversion]])''; the top of the stratosphere has a temperature of about 270 [[Kelvin|K]] (−3[[°C]] or 26.6[[°F]]).<ref>{{Cite book |last1=Seinfeld |first1=J. H. |title=Atmospheric chemistry and physics: from air pollution to climate change |last2=Pandis |first2=S. N. |date=2006 |publisher=Wiley |isbn=978-0-471-72018-8 |edition=2nd |location=Hoboken, NJ |pages=8}}</ref>

This vertical [[Atmospheric stratification|stratification]], with warmer layers above and cooler layers below, makes the stratosphere dynamically stable: there is no regular [[convection]] and associated [[turbulence]] in this part of the atmosphere. However, exceptionally energetic convection processes, such as volcanic [[eruption column]]s and [[overshooting top]]s in severe [[Supercell|supercell thunderstorms]], may carry convection into the stratosphere on a very local and temporary basis. Overall, the attenuation of solar UV at wavelengths that damage DNA by the ozone layer allows life to exist on the planet's surface outside of the ocean. All air entering the stratosphere must pass through the [[tropopause]], the temperature minimum that divides the troposphere and stratosphere. The rising air is literally freeze-dried; the stratosphere is a very dry place. The top of the stratosphere is called the [[stratopause]], above which the temperature decreases with height.

=== Formation and destruction ===
{{Further|Ozone–oxygen cycle}}

Paul J. Crutzen, Mario J. Molina and F. Sherwood Rowland were awarded the Nobel Prize in Chemistry in 1995 for their work describing the formation and decomposition of stratospheric ozone.<ref>{{Cite web|title=The Nobel Prize in Chemistry 1995|url=https://www.nobelprize.org/prizes/chemistry/1995/summary/|access-date=2020-07-21|website=NobelPrize.org|language=en-US}}</ref>

== Aircraft flight ==
[[File:Boeing_737_view_1.jpg|alt=A generic Boeing 737-800 cruising at 32,000 feet. Below it is a pack of clouds. Above it is a vivid, ambient blue sky.|left|thumb|262x262px|Aircraft typically cruise at the stratosphere to avoid [[turbulence]] rampant in the [[troposphere]]. The blue beam in this image is the [[ozone layer]], beaming further to the [[mesosphere]]. The [[ozone]] heats the stratosphere, making conditions stable. The stratosphere is also the altitude limit of jets and [[Weather balloon|weather balloons]], as air is roughly a thousand times thinner there than at the troposphere.<ref>{{Cite web |last= |first= |date= |title=The Stratosphere – overview |url=https://scied.ucar.edu/learning-zone/atmosphere/stratosphere-overview#:~:text=Commercial%20jet%20aircraft%20fly%20in,the%20lower,%20more%20humid%20troposphere. |access-date=2021-02-06 |website= |publisher=[[National Center for Science Education]]}}</ref>]]
Commercial [[airliner]]s typically cruise at altitudes of {{convert|9|–|12|km|ft|abbr=on}} which is in the lower reaches of the stratosphere in temperate latitudes.<ref>{{cite web |accessdate=2022-01-21 |editor-first=Glenn |editor-last=Elert |first=Daniel |last=Cheng |title=Altitude of a commercial jet airplane |url=https://hypertextbook.com/facts/2003/DanielCheng.shtml |website=The Physics Factbook |year=2003}}</ref> This optimizes [[fuel efficiency]], mostly due to the low temperatures encountered near the tropopause and low air density, reducing [[parasitic drag]] on the [[airframe]]. Stated another way, it allows the airliner to fly faster while maintaining lift equal to the weight of the plane. (The fuel consumption depends on the drag, which is related to the lift by the [[lift-to-drag ratio]].) It also allows the airplane to stay above the [[turbulence|turbulent]] weather of the troposphere.

The [[Concorde]] aircraft cruised at [[Mach number|Mach 2]] at about {{convert|60000|ft|km|0|abbr=on}}, and the [[SR-71]] cruised at Mach&nbsp;3 at {{convert|85000|ft|km|0|abbr=on}}, all within the stratosphere.

Because the temperature in the tropopause and lower stratosphere is largely constant with increasing altitude, very little convection and its resultant turbulence occurs there. Most turbulence at this altitude is caused by variations in the [[jet stream]] and other local wind shears, although areas of significant convective activity ([[thunderstorm]]s) in the troposphere below may produce turbulence as a result of [[convective overshoot]].

On October 24, 2014, [[Alan Eustace]] became the record holder for reaching the altitude record for a manned balloon at {{convert|135,890|ft|sigfig=5|abbr=on}}.<ref>{{Cite news |last=Markoff |first=John |date=2014-10-24 |title=Parachutist's Record Fall: Over 25 Miles in 15 Minutes (Published 2014) |language=en-US |work=The New York Times |url=https://www.nytimes.com/2014/10/25/science/alan-eustace-jumps-from-stratosphere-breaking-felix-baumgartners-world-record.html |access-date=2020-10-20 |issn=0362-4331}}</ref> Eustace also broke the world records for vertical speed skydiving, reached with a peak velocity of 1,321&nbsp;km/h (822&nbsp;mph) and total freefall distance of {{convert|123,414|ft|sigfig=5|abbr=on}}, lasting 4 minutes and 27 seconds.<ref>{{cite news |url=https://www.bbc.com/news/world-us-canada-29766189 |title=Google's Alan Eustace beats Baumgartner's skydiving record |newspaper=BBC News |url-status=live |archive-url=https://web.archive.org/web/20141025121736/http://www.bbc.com/news/world-us-canada-29766189 |archive-date=2014-10-25 |date=2014-10-24}}</ref>

== Circulation and mixing ==
The stratosphere is a region of intense interactions among radiative, [[dynamical]], and chemical processes, in which the horizontal mixing of gaseous components proceeds much more rapidly than does vertical mixing. The overall circulation of the stratosphere is termed as [[Brewer-Dobson circulation]], which is a single-celled circulation, spanning from the tropics up to the poles, consisting of the tropical upwelling of air from the tropical troposphere and the extra-tropical downwelling of air. Stratospheric circulation is a predominantly wave-driven circulation in that the tropical upwelling is induced by the wave force by the westward propagating [[Rossby waves]], in a phenomenon called Rossby-wave pumping.

An interesting feature of stratospheric circulation is the [[quasi-biennial oscillation]] (QBO) in the tropical latitudes, which is driven by [[gravity wave]]s that are convectively generated in the [[troposphere]]. The QBO induces a [[secondary circulation]] that is important for the global stratospheric transport of tracers, such as [[ozone]]<ref>N. Butchart, A.A. Scaife, J. Austin, S.H.E. Hare, J.R. Knight. ''[http://onlinelibrary.wiley.com/doi/10.1029/2002JD003004/abstract Quasi-biennial oscillation in ozone in a coupled chemistry-climate model] {{webarchive|url=https://web.archive.org/web/20140518230712/http://onlinelibrary.wiley.com/doi/10.1029/2002JD003004/abstract |date=2014-05-18 }}'', Journal of Geophysical Research.</ref> or [[water vapor]].

Another large-scale feature that significantly influences stratospheric circulation is the breaking planetary waves<ref>[[Michael E. McIntyre|M.E. McIntyre]], T.N. Palmer. ''[http://www.nature.com/nature/journal/v305/n5935/abs/305593a0.html Breaking planetary waves in the stratosphere] {{webarchive|url=https://web.archive.org/web/20170317055813/http://www.nature.com/nature/journal/v305/n5935/abs/305593a0.html |date=2017-03-17 }}'', Nature.</ref> resulting in intense quasi-horizontal mixing in the midlatitudes. This breaking is much more pronounced in the winter hemisphere where this region is called the surf zone. This breaking is caused due to a highly non-linear interaction between the vertically propagating planetary waves and the isolated high [[potential vorticity]] region known as the [[polar vortex]]. The resultant breaking causes large-scale mixing of air and other trace gases throughout the midlatitude surf zone. The timescale of this rapid mixing is much smaller than the much slower timescales of upwelling in the tropics and downwelling in the extratropics.

During northern hemispheric winters, [[sudden stratospheric warmings]], caused by the absorption of [[Rossby wave]]s in the stratosphere, can be observed in approximately half of the winters when easterly winds develop in the stratosphere. These events often precede unusual winter weather <ref>M.P. Baldwin and T.J. Dunkerton. ''[https://www.science.org/doi/abs/10.1126/science.1063315 Stratospheric Harbingers of Anomalous Weather Regimes] {{webarchive|url=https://web.archive.org/web/20140112084150/http://www.sciencemag.org/content/294/5542/581.short |date=2014-01-12 }}'', Science Magazine.</ref> and may even be responsible for the cold European winters of the 1960s.<ref>A.A. Scaife, J.R. Knight, G.K. Vallis, C.K. Folland. ''[http://onlinelibrary.wiley.com/doi/10.1029/2005GL023226/abstract A stratospheric influence on the winter NAO and North Atlantic surface climate] {{webarchive|url=https://web.archive.org/web/20140518230707/http://onlinelibrary.wiley.com/doi/10.1029/2005GL023226/abstract |date=2014-05-18 }}'', Geophysical Research Letters.</ref>

Stratospheric warming of the polar vortex results in its weakening.<ref>{{Cite web|title=How Sudden Stratospheric Warming Affects the Whole Atmosphere|url=https://eos.org/features/how-sudden-stratospheric-warming-affects-the-whole-atmosphere|access-date=2020-07-21|website=Eos|date=20 March 2018|language=en-US}}</ref> When the vortex is strong, it keeps the cold, high-pressure air masses ''contained'' in the [[Arctic]]; when the vortex weakens, air masses move equatorward, and results in rapid changes of weather in the mid latitudes.

==Upper-atmospheric lightning==
[[File:Gigantic jet NOIRLab.jpg|thumb|Lightning extending above the [[troposphere]] into the stratosphere as [[blue jet]] and reaching into the [[mesosphere]] as red [[Sprite (lightning)|sprite]]]] 
{{main|Upper-atmospheric lightning}}

Upper-atmospheric lightning is a family of short-lived electrical breakdown phenomena that occur well above the altitudes of normal [[lightning]] and storm clouds. Upper-atmospheric lightning is believed to be electrically induced forms of luminous [[Plasma (physics)|plasma]]. Lightning extending above the [[troposphere]] into the stratosphere is referred to as [[blue jet]], and that reaching into the [[mesosphere]] as red [[Sprite (lightning)|sprite]].

== Life ==
[[Bacteria]]l life survives in the stratosphere, making it a part of the [[biosphere]].<ref name="DasSarmaDasSarma2018">{{cite journal|last1=DasSarma|first1=Priya|last2=DasSarma|first2=Shiladitya|title=Survival of microbes in Earth's stratosphere|journal=Current Opinion in Microbiology|volume=43|year=2018|pages=24–30|issn=1369-5274|doi=10.1016/j.mib.2017.11.002|pmid=29156444|bibcode=2018COMb...43...24D |s2cid=19041112}}</ref> In 2001, dust was collected at a height of 41 kilometres in a high-altitude balloon experiment and was found to contain bacterial material when examined later in the laboratory.<ref name="Woolfson2013">{{cite book|author=Michael Mark Woolfson|author-link=Michael Woolfson|title=Time, Space, Stars & Man: The Story of the Big Bang|url=https://books.google.com/books?id=JYH0L2tLYpcC|year=2013|publisher=World Scientific|isbn=978-1-84816-933-3|page=388}}</ref>

== See also ==
* [[Le Grand Saut]]
* [[Lockheed U-2]]
* [[Overshooting top]]
* [[Ozone depletion]]
* [[Paris Gun]] (projectile was the first artificial object to reach the upper stratosphere)
* [[Perlan Project]]
* [[Project Excelsior]], world record for highest recorded jump 1961–2012
* [[Red Bull Stratos]], world record for highest recorded jump 2012–2014
* [[RQ-4 Global Hawk]]
* [[Service ceiling]]
* [[Upper-atmospheric lightning]]
* [[Sudden stratospheric warming]]
{{-}}

== References ==
{{Reflist}}

== External links ==
{{Wiktionary|stratosphere}}
*{{Commonscatinline|Stratosphere}}
*[https://earth.nullschool.net/#current/wind/isobaric/10hPa/overlay=temp/winkel3/ Current map of global winds and temperatures at the 10 hPa level.]

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