atmospheric pressure

(redirected from High-pressure system)
Also found in: Dictionary, Thesaurus, Medical.

atmospheric pressure

The force per unit area (i.e. pressure) exerted by a column of atmosphere extending vertically upwards to the limit of the atmosphere. It is usually expressed in millibars (mb) or newtons per square meter (N m–2). The standard atmospheric pressure at the Earth's surface at sea level is 1013 mb or 101 325 N m–2. On the surface of Venus and Mars the atmospheric pressure is about 90 000 mb and 7.5 mb, respectively.
Collins Dictionary of Astronomy © Market House Books Ltd, 2006
The following article is from The Great Soviet Encyclopedia (1979). It might be outdated or ideologically biased.

Atmospheric Pressure


the hydrostatic pressure exerted by the atmosphere on all objects in it. Atmospheric pressure is a fundamental characteristic of the atmosphere’s condition; at each point in the atmosphere it is determined by the weight of the overlying air. Atmospheric pressure decreases with height; its dependence on height is expressed by the barometric formula. Atmospheric pressure is measured by a barometer and is expressed in millibars (mbar), in newtons per sq m (N/m2), or by the height of a column of mercury in mm in a barometer brought to 0° C and normal gravity value (at sea level and 45° latitude). Normal atmospheric pressure is considered to be 760 mm Hg = 1,013.25 mbar = 101,325 N/m2. At a height of 5 km it is approximately half the value at the earth’s surface.

Atmospheric pressure at the earth’s surface varies from place to place and with time. Of particular importance are the nonperiodic variations associated with the onset, development, and dissolution of slowly moving high-pressure regions called anticyclones and vast, relatively fast-moving vortices, or cyclones, in which low pressure prevails. The extreme values of atmospheric pressure observed so far (at sea level) are 808.7 and 684.0 mm Hg. However, despite the large variability, the distribution of average monthly values at the earth’s surface each year is approximately the same. The average annual atmospheric pressure is low at the equator and has a minimum at about 10° N lat. It then increases and reaches a maximum at 30°-35° north and south latitudes; again it decreases, reaching a minimum at 60°-65°, but at the poles it increases again. This latitudinal distribution of atmospheric pressure is considerably influenced by the time of the year and the nature of the continental and oceanic layout. In winter there is a high-pressure region over the cold continents. Thus, latitudinal distribution is disturbed, and the pressure field is divided into a series of high-and low-pressure regions called centers of atmospheric action. The horizontal distribution of pressure becomes simpler with height, approaching the latitudinal distribution. Starting at a height of approximately 5 km, the atmospheric pressure diminishes from the equator to the poles over the entire globe.

Two maxima are observed in the diurnal variation—at 9–10 A.M. and at 9–10 P.M. Minima occur at 3–4 P.M. and 3–4 P.M. The diurnal variation is especially regular in tropical countries where the daytime variation reaches 2.4 mm Hg and nighttime 1.6 mm Hg. The amplitude of the pressure change decreases with increasing latitude, but at the same time the nonperiodic pressure variations become stronger.


Khrgian, A. Kh. Fizika atmosfery, 2nd ed., ch. V. Moscow, 1958.
Burgess, E. K granitsam prostranstva. Moscow, 1957. (Translated from English.)
The Great Soviet Encyclopedia, 3rd Edition (1970-1979). © 2010 The Gale Group, Inc. All rights reserved.

atmospheric pressure

[¦at·mə¦sfir·ik ′presh·ər]
The pressure at any point in an atmosphere due solely to the weight of the atmospheric gases above the point concerned. Also known as barometric pressure.
McGraw-Hill Dictionary of Scientific & Technical Terms, 6E, Copyright © 2003 by The McGraw-Hill Companies, Inc.

atmospheric pressure, barometric pressure

The pressure exerted by the earth’s atmosphere; under standard conditions equal to 14.7 lb per sq in. (1.01 × 106 pascals) equivalent to the pressure exerted by a column of mercury 29.9 in. (76.0 cm) high.
McGraw-Hill Dictionary of Architecture and Construction. Copyright © 2003 by McGraw-Hill Companies, Inc.
References in periodicals archive ?
But a comparison of weather data to models looking at La Ni[+ or -]a effects showed that the rain-blocking high-pressure system in the winter of 1933-34 overrode the effects of La Ni[+ or -]a for the western states.
The Japanese Archipelago, including Honshu, is forecast to have many sunny days in the weeks following the raining season because a high-pressure system in the Pacific is expected to cover the area, it added.
Q We have a leaking flange on a high-pressure system that requires a repair to take us through to our next scheduled shutdown.
Northern Kyushu in southwestern Japan and the Chugoku region in western Japan received 10-20 mm per hour early Tuesday as a high-pressure system over the Pacific Ocean pushed wet air into a low-pressure zone.
The drought began when a high-pressure system (weather pattern in which dense dry air keeps out rain) stalled over parts of the Midwest and Northeast for two months (see diagram, above).
Jerome Namias of the Scripps Institution of Oceanography in La Jolla, Calif., proposed this idea in 1988 when he reported that an unusually strong high-pressure system developed in the North Pacific before quakes struck southern California in 1986 and 1987 (SN:5/7/88, p.299).
If a high-pressure system over the Pacific strengthens, Maria will veer more towards the south in the direction of northern Taiwan, if the high pressure system weakens, it will spiral northward and will have less of an impact on the country.
With the high-pressure system affecting the region, temperatures are expected to drop over the next three days, and some isolated rains are forecast for Friday.
A high-pressure system has settled in over much of Western Oregon, bringing air stagnation that is likely to cause wood stove particulate emissions to build up and sully the air.
As we approach the summer months, the let stream continues northwards, allowing the Azores High--a high-pressure system that normally sits over the Azores in the mid-Atlantic--to spread its influence towards the UK reducing the chance of showers.
According to the agency, northeast Japan is under a low-pressure system and rainy front, and unsettled weather will probably continue there for a week or so as a damp east wind is blowing due to a high-pressure system on the Sea of Okhotsk.

Full browser ?