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 In fluid dynamics, a fluid parcel, also known as a fluid element or material element, is an infinitesimal volume of fluid, identifiable throughout its dynamic history while moving with the fluid flow. As it moves, the mass of a fluid parcel remain ...

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 A high-pressure area, high, or anticyclone, is an area near the surface of a planet where the atmospheric pressure is greater than the pressure in the surrounding regions. Highs are middle-scale meteorological features that result from interpl ...

as more air moves into the same space: the polar highs are areas of almost constant subsidence, as are the

horse latitudes The horse latitudes are the latitudes about 30 degrees north and south of the Equator. They are characterized by sunny skies, calm winds, and very little precipitation. They are also known as subtropical ridges or highs. It is a high-pressu ...

, and the areas of subsidence are the sources of much of the

prevailing wind In meteorology, prevailing wind in a region of the Earth's surface is a surface wind that blows predominantly from a particular direction. The dominant winds are the trends in direction of wind with the highest speed over a particular point on t ...

s in the

Earth's atmosphere The atmosphere of Earth is composed of a layer of gas mixture that surrounds the Earth's planetary surface (both lands and oceans), known collectively as air, with variable quantities of suspended aerosols and particulates (which create weathe ...

. 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 Fog is a visible aerosol consisting of tiny water droplets or ice crystals suspended in the air at or near the Earth's surface. Reprint from Fog can be considered a type of low-lying cloud usually resembling stratus and is heavily influenc ...

; on the other hand, its absence may cause

air stagnation Air stagnation is a meteorological condition that occurs when there is a lack of atmospheric movement, leading to the accumulation of pollutants and particles that can decline the air quality in a particular region. This condition typically correla ...

. An extreme form of subsidence is a ''

downburst In meteorology, a downburst is a strong downward and outward gushing wind system that emanates from a point source above and blows radially, that is, in straight lines in all directions from the area of impact at surface level. It originate ...

'', 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 In meteorology, an updraft (British English: ''up-draught'') is a small-scale current of rising air, often within a cloud. Overview Vertical drafts, known as updrafts or downdrafts, are localized regions of warm or cool air that move vertically ...

''.

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.

References

Atmosphere Meteorological phenomena {{meteorology-stub

Atmospheric pressure and atmospheric subsidence

See also

References