air mass


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air mass,

large body of air within the earth's atmosphereatmosphere
[Gr.,=sphere of air], the mixture of gases surrounding a celestial body with sufficient gravity to maintain it. Although some details about the atmospheres of other planets and satellites are known, only the earth's atmosphere has been well studied, the science of
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 in which temperature and humidity, although varying at different heights, remain similar throughout the body at any one height. Air masses form over parts of the earth's surface called source regions, which are large bodies of water or landmasses with relatively uniform topography, often ranging hundreds of thousands of square miles in area. When a body of air remains over a source region for days or weeks, it reaches an equilibrium with the surface. Radiation and convection exchanges between the surface and the air determines the air mass characteristics. Air masses formed over oceans generally contain more moisture than continental ones; air masses formed in polar latitudes are colder than those from the tropics. As an air mass moves away from its source region, it brings its particular weatherweather,
state of the atmosphere at a given time and place with regard to temperature, air pressure (see barometer), wind, humidity, cloudiness, and precipitation. The term weather
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 conditions to areas over which it travels. At the same time, its characteristic properties are slowly modified by exposure to new environments. The boundaries between air masses, called frontsfront,
in meteorology, zone of transition between adjacent air masses. If a cold air mass is advancing to replace a warmer one, their mutual boundary is termed a cold front; if the reverse, then the boundary is termed a warm front, whereas a stationary front indicates that no
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, are, typically, zones of rapid transition from cold to warm or from dry to moist air. Turbulence at the boundary often breeds low-pressure storms.

air mass

[′er ‚mas]
(meteorology)
An extensive body of the atmosphere which approximates horizontal homogeneity in its weather characteristics, particularly with reference to temperature and moisture distribution.

air mass

A body of air with nearly uniform conditions of temperature and humidity at any given level.
References in periodicals archive ?
This air mass is mostly just another form of polar maritime air, however it has a longer sea track that initially takes the air southwards over the North-Atlantic, then north-eastwards across the UK.
A cold polar high, high pressure or ridging aloft, and higher air mass humidity than normal are more likely to create these patterns.
i] are vectors of the optimization problem variables for the air mass flow rates, zone temperatures, and zone humidity ratios, respectively.
The cold air mass caused low temperatures along the Pacific coast.
But after receiving the stitches, the pontiff arrived on time for an open- air mass for 350,000 in the city of Sandomierz, with a bandage visible just below his skullcap.
The last column in this table, [DELTA] Air Mass, is the air mass of 62 [xi] -Cyg subtracted from the air mass of NGC 7027.
As a continental cold air mass blasted into Taiwan yesterday (March 9), snow began falling on Hehuanshan last night, and by this morning an accumulation of 6 cm of snow had been recorded, according to Liberty Times.
23 (Petra)-- The Kingdom will be affected on Tuesday by a cold air mass accompanied by a depression centered over Cyprus, pushing temperatures down and creating cold, cloudy conditions with rainfall in the central and northern parts of the Kingdom extending to the southwestern regions.
Their early work laid out the mathematics of forecasting and described fronts, showing that they are defined by a change in air mass density.
There is first of all the original cold air mass to the north of the front, a warm [air] mass to the south of the front with a stable air mass that is drier and warmer aloft over the warm air mass.
Waste air mass from the drying chamber and the condensation chamber contains volatile organic compounds.
In our skies the air mass feeding this cloud pattern may extend upward by another 5000 feet.