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Inversion (meteorology)

May 05, 2023

In meteorology, an inversion is a deviation from the normal change of an atmospheric property with altitude. It almost always refers to an inversion of the air temperature lapse rate, in which case it is called a temperature inversion. Normally, air temperature decreases with an increase in altitude, but during an inversion warmer air is held above cooler air.[2]

Temperature inversion in the Lake District, England, forms clouds at a low level beneath clear skies.
Smoke rising in Lochcarron, Scotland, is stopped by an overlying layer of warmer air (2006).
Smog trapped over the city of Almaty, Kazakhstan during a temperature inversion.
Smoke-filled canyons in northern Arizona, 2019. During morning and evening hours, dense smoke often settles in low-lying areas and becomes trapped due to temperature inversions—when a layer within the lower atmosphere acts as a lid and prevents vertical mixing of the air. Steep canyon walls act as a horizontal barrier, concentrating the smoke within the deepest parts of the canyon and increasing the strength of the inversion.[1]

An inversion traps air pollution, such as smog, close to the ground. An inversion can also suppress convection by acting as a "cap". If this cap is broken for any of several reasons, convection of any moisture present can then erupt into violent thunderstorms. Temperature inversion can notoriously result in freezing rain in cold climates.

Normal atmospheric conditions

Usually, within the lower atmosphere (the troposphere) the air near the surface of the Earth is warmer than the air above it, largely because the atmosphere is heated from below as solar radiation warms the Earth's surface, which in turn then warms the layer of the atmosphere directly above it, e.g., by thermals (convective heat transfer).[3] Air temperature also decreases with an increase in altitude because higher air is at lower pressure, and lower pressure results in a lower temperature, following the ideal gas law and adiabatic lapse rate.

Description

 
Height (y-axis) versus temperature (x-axis) under normal atmospheric conditions (black line). When the layer from 6–8 kilometres (4–5 miles) (designated A-B) descends dry adiabatically , the result is the inversion seen near the ground at 1–2 kilometres (1–1 mile) (C-D).
 
Klagenfurter Becken (Austria) in December 2015: on Mount Goritschnigkogel there is a distinct inverse hoarfrost margin.

Under the right conditions, the normal vertical temperature gradient is inverted so that the air is colder near the surface of the Earth. This can occur when, for example, a warmer, less-dense air mass moves over a cooler, denser air mass. This type of inversion occurs in the vicinity of warm fronts, and also in areas of oceanic upwelling such as along the California coast in the United States. With sufficient humidity in the cooler layer, fog is typically present below the inversion cap. An inversion is also produced whenever radiation from the surface of the earth exceeds the amount of radiation received from the sun, which commonly occurs at night, or during the winter when the sun is very low in the sky. This effect is virtually confined to land regions as the ocean retains heat far longer. In the polar regions during winter, inversions are nearly always present over land.

A warmer air mass moving over a cooler one can "shut off" any convection which may be present in the cooler air mass: this is known as a capping inversion. However, if this cap is broken, either by extreme convection overcoming the cap or by the lifting effect of a front or a mountain range, the sudden release of bottled-up convective energy—like the bursting of a balloon—can result in severe thunderstorms. Such capping inversions typically precede the development of tornadoes in the Midwestern United States. In this instance, the "cooler" layer is quite warm but is still denser and usually cooler than the lower part of the inversion layer capping it.[4]

Subsidence inversion

An inversion can develop aloft as a result of air gradually sinking over a wide area and being warmed by adiabatic compression, usually associated with subtropical high-pressure areas.[5] A stable marine layer may then develop over the ocean as a result. As this layer moves over progressively warmer waters, however, turbulence within the marine layer can gradually lift the inversion layer to higher altitudes, and eventually even pierce it, producing thunderstorms, and under the right circumstances, tropical cyclones. The accumulated smog and dust under the inversion quickly taints the sky reddish, easily seen on sunny days.

Atmospheric consequences

 
A Fata Morgana (or mirage) of a ship is due to an inversion (2008).
 
Winter smoke in Shanghai, China, with a clear border-layer for the vertical air-spread (1993).
 
A temperature inversion in Bratislava, Slovakia, viewing the top of Nový Most (2005).
 
Inversion-created smog in Nowa Ruda, Poland, 2017

Temperature inversions stop atmospheric convection (which is normally present) from happening in the affected area and can lead to high concentrations of atmospheric pollutants. Cities especially suffer from the effects of temperature inversions because they both produce more atmospheric pollutants and have higher thermal masses than rural areas, resulting in more frequent inversions with higher concentrations of pollutants. The effects are even more pronounced when a city is surrounded by hills or mountains since they form an additional barrier to air circulation. During a severe inversion, trapped air pollutants form a brownish haze that can cause respiratory problems. The Great Smog of 1952 in London, England, is one of the most serious examples of such an inversion. It was blamed for an estimated 10,000 to 12,000 deaths.[6]

Sometimes the inversion layer is at a high enough altitude that cumulus clouds can condense but can only spread out under the inversion layer. This decreases the amount of sunlight reaching the ground and prevents new thermals from forming. As the clouds disperse, sunny weather replaces cloudiness in a cycle that can occur more than once a day.

Wave propagation

Light

As the temperature of air increases, the index of refraction of air decreases, a side effect of hotter air being less dense. Normally this results in distant objects being shortened vertically, an effect that is easy to see at sunset when the sun is visible as an oval. In an inversion, the normal pattern is reversed, and distant objects are instead stretched out or appear to be above the horizon, leading to the phenomenon known as a Fata Morgana or mirage.

Inversions can magnify the so-called "green flash"—a phenomenon occurring at sunrise or sunset, usually visible for a few seconds, in which the sun's green light is isolated due to dispersion.[7] The shorter wavelength is refracted most, with the blue component of sunlight "completely scattered out by Rayleigh scattering", making green the first or last light from the upper rim of the solar disc to be seen.[8]

Radio waves

Main article: Super refraction

Very high frequency radio waves can be refracted by inversions, making it possible to hear FM radio or watch VHF low-band television broadcasts from long distances on foggy nights. The signal, which would normally be refracted up and away into space, is instead refracted down towards the earth by the temperature-inversion boundary layer. This phenomenon is called tropospheric ducting. Along coastlines during Autumn and Spring, due to multiple stations being simultaneously present because of reduced propagation losses, many FM radio stations are plagued by severe signal degradation disrupting reception. In higher frequencies such as microwaves, such refraction causes multipath propagation and fading.

Sound

When an inversion layer is present, if a sound or explosion occurs at ground level, the sound wave is refracted by the temperature gradient (which affects sound speed) and returns to the ground. The sound, therefore, travels much better than normal. This is noticeable in areas around airports, where the sound of aircraft taking off and landing often can be heard at greater distances around dawn than at other times of day, and inversion thunder which is significantly louder and travels further than when it is produced by lightning strikes under normal conditions.[9]

Shock waves

The shock wave from an explosion can be reflected by an inversion layer in much the same way as it bounces off the ground in an air-burst and can cause additional damage as a result. This phenomenon killed two people in the Soviet RDS-37 nuclear test when a building collapsed.[10][11]

See also

References

  1. ^ Smoke Filled Canyons, Arizona
  2. ^ Service, NOAA's National Weather. "Glossary – NOAA's National Weather Service". w1.weather.gov. Retrieved January 19, 2017.
  3. ^ Nagle, Garrett, and Paul Guinness. Cambridge International A and AS Level Geography. Hodder Education, 2011. 41. Print.
  4. ^ Oke, Tim; Mills, Gerald; Christen, Andrea; Voogt, James (2017). Urban Climates (1st ed.). Cambridge: Cambridge University Press. pp. 30–35. doi:10.1017/9781139016476. ISBN 978-0-521-84950-0. Retrieved June 21, 2022.
  5. ^ Wallace and Hobbs (2006) Atmospheric Science: An Introductory Survey
  6. ^ Bell, M.L.; Davis, D.L.; Fletcher, T. (2004). "A Retrospective Assessment of Mortality from the London Smog Episode of 1952: The Role of Influenza and Pollution". Environ Health Perspect. 112 (1, January): 6–8. doi:10.1289/ehp.6539. PMC 1241789. PMID 14698923.
  7. ^ ben Aroush, Tomer; Boulahjar, Saber; Lipson, Stephen G (December 13, 2017). "Observing the green flash in the laboratory". European Journal of Physics. 39 (1): 2. doi:10.1088/1361-6404/aa90f5. S2CID 125714499. Retrieved June 21, 2022.
  8. ^ ben Aroush, Tomer; Boulahjar, Saber; Lipson, Stephen G (December 13, 2017). "Observing the green flash in the laboratory". European Journal of Physics. 39 (1): 2. doi:10.1088/1361-6404/aa90f5. S2CID 125714499. Retrieved June 21, 2022.
  9. ^ Dean A. Pollet and Micheal M. Kordich, User's guide for the Sound Intensity Prediction System (SIPS) as installed at the Naval Explosive Ordnance Disposal Technology Division (Naveodtechdiv). Systems Department February 2000. DTIC.mil
  10. ^ Johnston, Wm. Robert. "RDS-37 Nuclear Test, 1955". Retrieved April 11, 2014.
  11. ^ "RDS-37: The Soviet Hydrogen Bomb". Retrieved December 26, 2015.

External links

  • 'Fire inversions' lock smoke in valleys
  •   The dictionary definition of temperature inversion at Wiktionary
 
Wikimedia Commons has media related to Meteorological inversion.

May 05, 2023
inversion, meteorology, this, article, needs, additional, citations, verification, please, help, improve, this, article, adding, citations, reliable, sources, unsourced, material, challenged, removed, find, sources, inversion, meteorology, news, newspapers, bo. This article needs additional citations for verification Please help improve this article by adding citations to reliable sources Unsourced material may be challenged and removed Find sources Inversion meteorology news newspapers books scholar JSTOR May 2020 Learn how and when to remove this template message This article may be too technical for most readers to understand Please help improve it to make it understandable to non experts without removing the technical details July 2022 Learn how and when to remove this template message In meteorology an inversion is a deviation from the normal change of an atmospheric property with altitude It almost always refers to an inversion of the air temperature lapse rate in which case it is called a temperature inversion Normally air temperature decreases with an increase in altitude but during an inversion warmer air is held above cooler air 2 Temperature inversion in the Lake District England forms clouds at a low level beneath clear skies Smoke rising in Lochcarron Scotland is stopped by an overlying layer of warmer air 2006 Smog trapped over the city of Almaty Kazakhstan during a temperature inversion Smoke filled canyons in northern Arizona 2019 During morning and evening hours dense smoke often settles in low lying areas and becomes trapped due to temperature inversions when a layer within the lower atmosphere acts as a lid and prevents vertical mixing of the air Steep canyon walls act as a horizontal barrier concentrating the smoke within the deepest parts of the canyon and increasing the strength of the inversion 1 An inversion traps air pollution such as smog close to the ground An inversion can also suppress convection by acting as a cap If this cap is broken for any of several reasons convection of any moisture present can then erupt into violent thunderstorms Temperature inversion can notoriously result in freezing rain in cold climates Contents 1 Normal atmospheric conditions 2 Description 3 Subsidence inversion 4 Atmospheric consequences 5 Wave propagation 5 1 Light 5 2 Radio waves 5 3 Sound 5 3 1 Shock waves 6 See also 7 References 8 External linksNormal atmospheric conditions EditUsually within the lower atmosphere the troposphere the air near the surface of the Earth is warmer than the air above it largely because the atmosphere is heated from below as solar radiation warms the Earth s surface which in turn then warms the layer of the atmosphere directly above it e g by thermals convective heat transfer 3 Air temperature also decreases with an increase in altitude because higher air is at lower pressure and lower pressure results in a lower temperature following the ideal gas law and adiabatic lapse rate Description Edit Height y axis versus temperature x axis under normal atmospheric conditions black line When the layer from 6 8 kilometres 4 5 miles designated A B descends dry adiabatically the result is the inversion seen near the ground at 1 2 kilometres 1 1 mile C D Klagenfurter Becken Austria in December 2015 on Mount Goritschnigkogel there is a distinct inverse hoarfrost margin Under the right conditions the normal vertical temperature gradient is inverted so that the air is colder near the surface of the Earth This can occur when for example a warmer less dense air mass moves over a cooler denser air mass This type of inversion occurs in the vicinity of warm fronts and also in areas of oceanic upwelling such as along the California coast in the United States With sufficient humidity in the cooler layer fog is typically present below the inversion cap An inversion is also produced whenever radiation from the surface of the earth exceeds the amount of radiation received from the sun which commonly occurs at night or during the winter when the sun is very low in the sky This effect is virtually confined to land regions as the ocean retains heat far longer In the polar regions during winter inversions are nearly always present over land A warmer air mass moving over a cooler one can shut off any convection which may be present in the cooler air mass this is known as a capping inversion However if this cap is broken either by extreme convection overcoming the cap or by the lifting effect of a front or a mountain range the sudden release of bottled up convective energy like the bursting of a balloon can result in severe thunderstorms Such capping inversions typically precede the development of tornadoes in the Midwestern United States In this instance the cooler layer is quite warm but is still denser and usually cooler than the lower part of the inversion layer capping it 4 Subsidence inversion EditAn inversion can develop aloft as a result of air gradually sinking over a wide area and being warmed by adiabatic compression usually associated with subtropical high pressure areas 5 A stable marine layer may then develop over the ocean as a result As this layer moves over progressively warmer waters however turbulence within the marine layer can gradually lift the inversion layer to higher altitudes and eventually even pierce it producing thunderstorms and under the right circumstances tropical cyclones The accumulated smog and dust under the inversion quickly taints the sky reddish easily seen on sunny days Atmospheric consequences Edit A Fata Morgana or mirage of a ship is due to an inversion 2008 Winter smoke in Shanghai China with a clear border layer for the vertical air spread 1993 A temperature inversion in Bratislava Slovakia viewing the top of Novy Most 2005 Inversion created smog in Nowa Ruda Poland 2017 Temperature inversions stop atmospheric convection which is normally present from happening in the affected area and can lead to high concentrations of atmospheric pollutants Cities especially suffer from the effects of temperature inversions because they both produce more atmospheric pollutants and have higher thermal masses than rural areas resulting in more frequent inversions with higher concentrations of pollutants The effects are even more pronounced when a city is surrounded by hills or mountains since they form an additional barrier to air circulation During a severe inversion trapped air pollutants form a brownish haze that can cause respiratory problems The Great Smog of 1952 in London England is one of the most serious examples of such an inversion It was blamed for an estimated 10 000 to 12 000 deaths 6 Sometimes the inversion layer is at a high enough altitude that cumulus clouds can condense but can only spread out under the inversion layer This decreases the amount of sunlight reaching the ground and prevents new thermals from forming As the clouds disperse sunny weather replaces cloudiness in a cycle that can occur more than once a day Wave propagation EditLight Edit As the temperature of air increases the index of refraction of air decreases a side effect of hotter air being less dense Normally this results in distant objects being shortened vertically an effect that is easy to see at sunset when the sun is visible as an oval In an inversion the normal pattern is reversed and distant objects are instead stretched out or appear to be above the horizon leading to the phenomenon known as a Fata Morgana or mirage Inversions can magnify the so called green flash a phenomenon occurring at sunrise or sunset usually visible for a few seconds in which the sun s green light is isolated due to dispersion 7 The shorter wavelength is refracted most with the blue component of sunlight completely scattered out by Rayleigh scattering making green the first or last light from the upper rim of the solar disc to be seen 8 Radio waves Edit Main article Super refraction Very high frequency radio waves can be refracted by inversions making it possible to hear FM radio or watch VHF low band television broadcasts from long distances on foggy nights The signal which would normally be refracted up and away into space is instead refracted down towards the earth by the temperature inversion boundary layer This phenomenon is called tropospheric ducting Along coastlines during Autumn and Spring due to multiple stations being simultaneously present because of reduced propagation losses many FM radio stations are plagued by severe signal degradation disrupting reception In higher frequencies such as microwaves such refraction causes multipath propagation and fading Sound Edit When an inversion layer is present if a sound or explosion occurs at ground level the sound wave is refracted by the temperature gradient which affects sound speed and returns to the ground The sound therefore travels much better than normal This is noticeable in areas around airports where the sound of aircraft taking off and landing often can be heard at greater distances around dawn than at other times of day and inversion thunder which is significantly louder and travels further than when it is produced by lightning strikes under normal conditions 9 Shock waves Edit The shock wave from an explosion can be reflected by an inversion layer in much the same way as it bounces off the ground in an air burst and can cause additional damage as a result This phenomenon killed two people in the Soviet RDS 37 nuclear test when a building collapsed 10 11 See also Edit Weather portalAerosol Particulates Index of meteorology articlesReferences Edit Smoke Filled Canyons Arizona Service NOAA s National Weather Glossary NOAA s National Weather Service w1 weather gov Retrieved January 19 2017 Nagle Garrett and Paul Guinness Cambridge International A and AS Level Geography Hodder Education 2011 41 Print Oke Tim Mills Gerald Christen Andrea Voogt James 2017 Urban Climates 1st ed Cambridge Cambridge University Press pp 30 35 doi 10 1017 9781139016476 ISBN 978 0 521 84950 0 Retrieved June 21 2022 Wallace and Hobbs 2006 Atmospheric Science An Introductory Survey Bell M L Davis D L Fletcher T 2004 A Retrospective Assessment of Mortality from the London Smog Episode of 1952 The Role of Influenza and Pollution Environ Health Perspect 112 1 January 6 8 doi 10 1289 ehp 6539 PMC 1241789 PMID 14698923 ben Aroush Tomer Boulahjar Saber Lipson Stephen G December 13 2017 Observing the green flash in the laboratory European Journal of Physics 39 1 2 doi 10 1088 1361 6404 aa90f5 S2CID 125714499 Retrieved June 21 2022 ben Aroush Tomer Boulahjar Saber Lipson Stephen G December 13 2017 Observing the green flash in the laboratory European Journal of Physics 39 1 2 doi 10 1088 1361 6404 aa90f5 S2CID 125714499 Retrieved June 21 2022 Dean A Pollet and Micheal M Kordich User s guide for the Sound Intensity Prediction System SIPS as installed at the Naval Explosive Ordnance Disposal Technology Division Naveodtechdiv Systems Department February 2000 DTIC mil Johnston Wm Robert RDS 37 Nuclear Test 1955 Retrieved April 11 2014 RDS 37 The Soviet Hydrogen Bomb Retrieved December 26 2015 External links Edit Fire inversions lock smoke in valleys The dictionary definition of temperature inversion at Wiktionary Wikimedia Commons has media related to Meteorological inversion Retrieved from https en wikipedia org w index php title Inversion meteorology amp oldid 1152536975, wikipedia, wiki, book, books, library,

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