Stratosphere
The stratosphere (
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 20 km (66,000 ft; 12 mi), at midlatitudes around 10 km (33,000 ft; 6.2 mi), and at the poles about 7 km (23,000 ft; 4.3 mi).[4] Temperatures range from an average of −51 °C (−60 °F; 220 K) near the tropopause to an average of −15 °C (5.0 °F; 260 K) near the mesosphere.[5] Stratospheric temperatures also vary within the stratosphere as the seasons change, reaching particularly low temperatures in the polar night (winter).[6] Winds in the stratosphere can far exceed those in the troposphere, reaching near 60 m/s (220 km/h; 130 mph) in the Southern polar vortex.[6]
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 km (6.8-8.7 mi), which is the base of the lower stratosphere. This was based on temperature profiles from mostly unmanned and a few manned instrumented balloons.[7]
Ozone layer
The mechanism describing the formation of the ozone layer was described by British mathematician and
This vertical
Formation and destruction
Sydney Chapman gave a correct description of the source of stratospheric ozone and its ability to generate heat within the stratosphere;[citation needed] he also wrote that ozone may be destroyed by reacting with atomic oxygen, making two molecules of molecular oxygen. We now know that there are additional ozone loss mechanisms and that these mechanisms are catalytic, meaning that a small amount of the catalyst can destroy a great number of ozone molecules. The first is due to the reaction of hydroxyl radicals (•OH) with ozone. •OH is formed by the reaction of electrically excited oxygen atoms produced by ozone photolysis, with water vapor. While the stratosphere is dry, additional water vapor is produced in situ by the photochemical oxidation of methane (CH4). The HO2 radical produced by the reaction of OH with O3 is recycled to OH by reaction with oxygen atoms or ozone. In addition, solar proton events can significantly affect ozone levels via radiolysis with the subsequent formation of OH. Nitrous oxide (N2O) is produced by biological activity at the surface and is oxidised to NO in the stratosphere; the so-called NOx radical cycles also deplete stratospheric ozone. Finally, chlorofluorocarbon molecules are photolysed in the stratosphere releasing chlorine atoms that react with ozone giving ClO and O2. The chlorine atoms are recycled when ClO reacts with O in the upper stratosphere, or when ClO reacts with itself in the chemistry of the Antarctic ozone hole.
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.[10]
Aircraft flight
Commercial airliners typically cruise at altitudes of 9–12 km (30,000–39,000 ft) which is in the lower reaches of the stratosphere in temperate latitudes.[12] 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 turbulent weather of the troposphere.
The
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 (thunderstorms) 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 135,890 ft (41,419 m).[13] Eustace also broke the world records for vertical speed skydiving, reached with a peak velocity of 1,321 km/h (822 mph) and total freefall distance of 123,414 ft (37,617 m) – lasting four minutes and 27 seconds.[14]
Circulation and mixing
The stratosphere is a region of intense interactions among radiative,
An interesting feature of stratospheric circulation is the quasi-biennial oscillation (QBO) in the tropical latitudes, which is driven by gravity waves 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[15] or water vapor.
Another large-scale feature that significantly influences stratospheric circulation is the breaking planetary waves[16] 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,
Stratospheric warming of the polar vortex results in its weakening.[19] 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
Upper-atmospheric lightning is a family of short-lived electrical-breakdown phenomena that occur well above the altitudes of normal
Life
Bacteria
Bacterial life survives in the stratosphere, making it a part of the biosphere.[20] 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.[21]
Birds
Some bird species have been reported to fly at the upper levels of the troposphere. On November 29, 1973, a Rüppell's vulture (Gyps rueppelli) was ingested into a jet engine 11,278 m (37,000 ft) above the Ivory Coast.[22] Bar-headed geese (Anser indicus) sometimes migrate over Mount Everest, whose summit is 8,848 m (29,029 ft).[23][24]
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
References
- ^ "Atmospheric Temperature Trends, 1979–2005". NASA/Earth Observatory. 6 July 2007. Archived from the original on 5 September 2015. Retrieved 24 August 2015.
- ISBN 978-3-12-539683-8
- ^ "Stratosphere". Merriam-Webster.com Dictionary.
- ^ a b "The Stratosphere - overview". scied.ucar.edu. University Corporation for Atmospheric Research. Retrieved 25 July 2018.
- ^ "NWS JetStream - Layers of the Atmosphere". www.weather.gov.
- ^ a b "Nasa Ozone Watch: Polar vortex facts". ozonewatch.gsfc.nasa.gov.
- ISBN 978-3-933603-33-3
- ^ "CHAPTER 10. STRATOSPHERIC OZONE". acmg.seas.harvard.edu. Archived from the original on 2019-09-30. Retrieved 2020-10-20.
- ^ Seinfeld, J. H., and S. N.(2006), Atmospheric Chemistry and Physics: From Air Pollution to Climate Change 2nd ed, Wiley, New Jersey
- ^ "The Nobel Prize in Chemistry 1995". NobelPrize.org. Retrieved 2020-07-21.
- ^ "The Stratosphere - overview | UCAR Center for Science Education". National Center for Science Education. Retrieved 2021-02-06.
- ^ Cheng, Daniel (2003). Elert, Glenn (ed.). "Altitude of a commercial jet airplane". The Physics Factbook. Retrieved 2022-01-21.
- ISSN 0362-4331. Retrieved 2020-10-20.
- ^ "Google's Alan Eustace beats Baumgartner's skydiving record". BBC News. 2014-10-24. Archived from the original on 2014-10-25.
- ^ N.Butchart, A.A. Scaife, J. Austin, S.H.E. Hare, J.R. Knight. Quasi-biennial oscillation in ozone in a coupled chemistry-climate model Archived 2014-05-18 at the Wayback Machine, Journal of Geophysical Research.
- ^ M.E. McIntyre, T.N. Palmer. Breaking planetary waves in the stratosphere Archived 2017-03-17 at the Wayback Machine, Nature.
- ^ M.P. Baldwin and T.J. Dunkerton. 'Stratospheric Harbingers of Anomalous Weather Regimes Archived 2014-01-12 at the Wayback Machine, Science Magazine.
- ^ A.A. Scaife, J.R. Knight, G.K. Vallis, C.K. Folland. A stratospheric influence on the winter NAO and North Atlantic surface climate Archived 2014-05-18 at the Wayback Machine, Geophysical Research Letters.
- ^ "How Sudden Stratospheric Warming Affects the Whole Atmosphere". Eos. 20 March 2018. Retrieved 2020-07-21.
- S2CID 19041112.
- ISBN 978-1-84816-933-3.
- (PDF) from the original on 2014-02-22.
- ^ "Audubon: Birds". Audubonmagazine.org. Archived from the original on 2011-09-14. Retrieved 2011-11-08.
- ISBN 978-0-521-44822-2.