In meteorology, an air mass is a large volume of air having fairly uniform characteristics of temperature, atmospheric pressure, and water vapor content. Air masses cover many hundreds or thousands of square miles, and slowly change in accordance with the terrain they are over. // Meteorology (from Greek: μετέωρον, meteoron, high in the sky; and λόγος, logos, knowledge) is the interdisciplinary scientific study of the atmosphere that focuses on weather processes and forecasting. ... Look up air in Wiktionary, the free dictionary. ... For other uses, see Temperature (disambiguation). ... Diurnal (daily) rhythm of air pressure in northern Germany (black curve is air pressure) Atmospheric pressure is the pressure at any point in the Earths atmosphere. ... It has been suggested that multiple sections of steam be merged into this article or section. ...

Classification

Source regions of global air masses

Air masses are classified according to their temperature and moisture content. The temperature characteristics of an air mass are defined by the terms Arctic, Polar and Tropical, with arctic being the coldest and tropical being the warmest. The moisture content of an air mass are defined by the terms Maritime and Continental. Maritime air is a moist air mass, whereas Continental air is relatively dry. The temperature and moisture terms are then combined to describe the air mass. For example, a maritime tropical air mass would be warm and moist, and a continental arctic would be cold and dry. Image File history File links No higher resolution available. ... Image File history File links No higher resolution available. ... The red line indicates the 10°C isotherm in July, commonly used to define the Arctic region border Satellite image of the Arctic surface The Arctic is the region around the Earths North Pole, opposite the Antarctic region around the South Pole. ... Polar may refer to: Polsk Ost med KATING WAPOOOOW CHING CHING WOWOWOWOW/Gling, Oink oink. ... The tropics are the geographic region of the Earth centered on the equator and limited in latitude by the two tropics: the Tropic of Cancer in the north and the Tropic of Capricorn in the southern hemisphere. ... From the latin maritimus, maritime refers to things relating to the sea. ... Continental may refer to: The adjective of continent, such as in continental Europe, continental breakfast, or continental climate, or Continental Glacier; The culture of the continental nation states of Europe, inasmuch as it contrasts with the culture of Anglo-Saxon England; The Lincoln Continental, a car made by Lincoln division...

Movement and fronts

The air mass terms refer to the fact that air masses acquire the properties of the terrain over which they move. Cold arctic air masses are most common in the arctic regions and maritime air masses generally form over water. Air masses do move however, and a maritime air mass that moves over land will slowly lose its moisture and eventually become continental, just as a tropical air mass that moves north will cool and become polar, or even arctic. Air masses can not be defined by perfect lines or borders, however there is a very small region of interaction of two or more air masses where contact occurs. This region is called a weather front; visible and significant weather changes will occur there. Air masses do not mix, rather they move and displace each other. The associated fronts also move, thus causing weather changes for the terrain below. Fronts are always named for the air mass that is advancing. Thus a cold front would occur where a cooler air mass is displacing a warmer one. A guide to the symbols for weather fronts that may be found on a weather map: 1. ...

Air masses are not to be confused with small scale events like microbursts, they move much quicker. Though these smaller events do involve masses of air, the term air mass is reserved for weather systems that span large areas. A photograph of the surface curl soon after an intense microburst impacted the surface A microburst is a very localized column of sinking air, producing damaging divergent and straight-line winds at the surface that are similar to but distinguishable from tornadoes which generally have convergent damage. ...

Other air masses

In Europe an Equatorial air mass is often defined as an airmass developing in equatorial lows and distinguished from a tropical air mass, which develops in subtropical heights. Others define monsoon and superior air masses.

See also

• Weather front