air mass
UK /ˈɛː mas/ · US /ɛəɹ mæs/ noun
Forms air masses airmass
- noun (physics, meteorology) a widespread body of air, the properties of which can be identified as: (a) having been established while that air was situated over a particular region of the Earth's surface (airmass source region) and (b) undergoing specific modifications while in transit away from the source region. An air mass is often defined as a widespread body of air that is approximately homogeneous in its horizontal extent, particularly with reference to temperature and moisture distribution; in addition, the vertical temperature and moisture variations are approximately the same over its horizontal extent.
- noun (astronomy) The amount of air through which light from a celestial object passes, normalized to 1 for an object at zenith.
Etymology
From air + mass. Perhaps a calque of German Luftmasse.
Sources: Wiktionary — from the Wiktionary entry “air mass”, CC BY-SA 4.0. Details