temperature inversion


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temperature inversion,

condition in which the temperature of the atmosphere increases with altitude in contrast to the normal decrease with altitude. When temperature inversion occurs, cold air underlies warmer air at higher altitudes. Temperature inversion may occur during the passage of a cold front or result from the invasion of sea air by a cooler onshore breeze. Overnight radiative cooling of surface air often results in a nocturnal temperature inversion that is dissipated after sunrise by the warming of air near the ground. A more long-lived temperature inversion accompanies the dynamics of the large high-pressure systems depicted on weather maps. Descending currents of air near the center of the high-pressure system produce a warming (by adiabatic compression), causing air at middle altitudes to become warmer than the surface air. Rising currents of cool air lose their buoyancy and are thereby inhibited from rising further when they reach the warmer, less dense air in the upper layers of a temperature inversion. During a temperature inversion, air pollution released into the atmosphere's lowest layer is trapped there and can be removed only by strong horizontal winds. Because high-pressure systems often combine temperature inversion conditions and low wind speeds, their long residency over an industrial area usually results in episodes of severe smog.

Temperature Inversion

 

an increase in air temperature with increasing altitude, which is inverse to the usual decrease in temperature with altitude in the troposphere. Temperature inversions occur both near the earth’s surface (ground temperature inversions) and in the free atmosphere. Ground inversions usually form on windless nights (sometimes also during the day in winter) as a result of the intensive radiation of heat by the earth’s surface, which cools the surface itself and the adjacent layer of air. Ground inversions measure dozens and hundreds of meters thick. The increase of temperature in the inversion layer varies from tenths of a degree to more than 15°-20°C. Eastern Siberia and Antarctica have the most intense winter ground inversions. In the troposphere, above the surface layer, temperature inversions usually form in high-pressure areas owing to the sinking of air, which is accompanied by its compression and therefore heating (subsidence inversion). In the zones of atmospheric fronts, temperature inversions are created by warm air advected over the cold air beneath. In the upper layers of the atmosphere (the stratosphere, the mesosphere, and the thermosphere) temperature inversions occur as a result of the strong absorption of solar radiation. For example, at altitudes of from 20–30 to 50–60 km there is a temperature inversion related to the absorption of ultraviolet radiation of the sun by ozone. At the base of this layer the temperature ranges between — 50° and — 70°C, while at its upper boundary the temperature rises to between —10° and + 10°C. Intense temperature inversions begin at altitudes of 80–90 km and stretch for hundreds of kilometers upward; they are also caused by absorption of solar radiation.

Temperature inversions are barrier layers in the atmosphere. They obstruct the development of vertical air currents, and as a result water vapor, dust, and condensation nuclei accumulate beneath them. This leads to the formation of layers of haze, fog, and clouds. Mirages sometimes occur as a result of the anomalous refraction of light in temperature inversions. Atmospheric ducts, which promote long-distance propagation of radio waves, also form in temperature inversions.

REFERENCE

Khrgian, A. Kh. Fizika atmosfery. Leningrad, 1969.

S. M. SHMETER

temperature inversion

[′tem·prə·chər in‚vər·zhən]
(meteorology)
A layer in the atmosphere in which temperature increases with altitude; the principal characteristic of an inversion layer is its marked static stability, so that very little turbulent exchange can occur within it; strong wind shears often occur across inversion layers, and abrupt changes in concentrations of atmospheric particulates and atmospheric water vapor may be encountered on ascending through the inversion layer. Also known as thermal inversion.
(oceanography)
A layer of a large body of water in which temperature increases with depth.
References in periodicals archive ?
Similar temperature inversions occur in the stratospheres of other planets in our solar system, such as Jupiter and Saturn.
The results show that the temperature inversion during the course of study in Tehran has been settled in all seasons and due to qualification the inversion conditions, the temperature sustainability of earth surface has been settled and 80 percent of the days of four years was studied under dominant inversion conditions, but height of the layer of inversion varies according to changing the seasons, and the greatest circumference of the inversion has been in autumn and winter according to maps of Skew-T.
The temperature inversion had a major impact on the inside concentrations of three outside sources, but not the fourth.
On the other hand, following passage of the cold front on March 18, low-level temperature inversions developed (figures 5a through 5e).
The results of temperature inversion by both techniques show that probably some non-climatic effects (well shut-in periods, vertical and horizontal water flows, sedimentation, uplift, erosion, steep topography, lakes, vertical variation in heat flow, lateral thermal conductivity contrasts, thermal conductivity anisotropy, forest fires, farming, etc.
A PHS report released in 1949 reported that "no single substance" was responsible for the Donora deaths and laid major blame for the tragedy on the temperature inversion.
According to Kaness, he learned that the whole problem in the Southern California coastal area is caused by the well-known temperature inversion layer that exists quite a bit of the time.
After initially issuing flat denials of problems and then blaming a typical winter temperature inversion despite above-average temperatures throughout November and early December the government has since resorted to drastic compensatory measures like sudden two-day public holidays and harsh traffic-control directives (see the background in down14IranEnBaseApr4-11).
That means that in the fall, as the fall temperature inversion mixes water in the lake, the new intake might take in warmer water than what now flows from the existing release valves, Stine said.
Kloppers and Kroger (2005) investigated the effects of the temperature inversion profile on the performance of cooling towers.
Air pollution officials say the Antelope Valley is mostly likely to get high levels of ozone on days when a temperature inversion settles over the Los Angeles Basin, then gives up its pollutants to a breeze that blows them into the desert.
Called a temperature inversion -- where cold air gets trapped under warm air -- this barrier is the same kind that holds smog over Los Angeles and Denver.

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