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In meteorology
Meteorology is the scientific study of the Earth's atmosphere and short-term atmospheric phenomena (i.e. weather), with a focus on weather forecasting. It has applications in the military, aviation, energy production, transport, agricultur ...
, subsidence is the downward movement of an air parcel as it cools and becomes denser. By contrast, warm air becomes less dense and moves upwards (atmospheric convection
Atmospheric convection is the vertical transport of heat and moisture in the atmosphere. It occurs when warmer, less dense air rises, while cooler, denser air sinks.
This process is driven by parcel-environment instability, meaning that a "par ...
).
Atmospheric subsidence generally creates a high-pressure area as more air moves into the same space: the polar highs are areas of almost constant subsidence, as are the horse latitudes, and the areas of subsidence are the sources of much of the prevailing winds in the Earth's atmosphere.
Subsidence also causes many smaller-scale weather
Weather is the state of the atmosphere, describing for example the degree to which it is hot or cold, wet or dry, calm or stormy, clear or cloud cover, cloudy. On Earth, most weather phenomena occur in the lowest layer of the planet's atmo ...
phenomena, such as morning fog; on the other hand, its absence may cause air stagnation. An extreme form of subsidence is a '' downburst'', which can result in damage similar to that produced by a tornado
A tornado is a violently rotating column of air that is in contact with the surface of Earth and a cumulonimbus cloud or, in rare cases, the base of a cumulus cloud. It is often referred to as a twister, whirlwind or cyclone, although the ...
. A milder form of subsidence is referred to as '' downdraft''.
Atmospheric pressure and atmospheric subsidence
The Dosen barometer (pictured) clearly relates high pressure with fine weather, as seen in its dial. This is because high pressure zones are subsidence zones, with dry and cool air descending and, therefore, clear skies and good weather.See also
* Diathermancy *Convection
Convection is single or Multiphase flow, multiphase fluid flow that occurs Spontaneous process, spontaneously through the combined effects of material property heterogeneity and body forces on a fluid, most commonly density and gravity (see buoy ...
References
Atmosphere Meteorological phenomena {{meteorology-stub