AIR MASS

n. section of air that maintains a consistent temperature and pressure

For airmass in astronomy, see airmass. 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.
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Noun
1. a large body of air with uniform characteristics horizontally
(hypernym) atmosphere, atmospheric state
(hyponym) high, high pressure

A large volume of air with certain meteorological or polluted characteristics--e.g., a heat inversion or smogginess--while in one location. The characteristics can change as the air mass moves away.

Synonyms and related words:
anticyclone, cold front, cold sector, cyclone, front, high, high-pressure area, isobar, isometric, isometric line, isopiestic line, isotherm, isothermal line, low, low-pressure area, occluded front, polar front, squall line, stationary front, warm front, weather map, wind-shift line,