air mass

American  

noun

1. a body of air covering a relatively wide area, exhibiting approximately uniform properties through any horizontal section.

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air mass British  

noun

1. a large body of air having characteristics of temperature, moisture, and pressure that are approximately uniform horizontally

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air mass Scientific  

1. A widespread body of air that originates over a large area of land or ocean and assumes the temperature and humidity of that area, with characteristics distributed fairly evenly throughout the horizontal layers of the mass. Air that stands over the Caribbean Sea, for example, becomes a warm, humid maritime tropical air mass, while air that lies in the Arctic regions of northern Canada takes on the cold and dry characteristics of its surroundings and becomes a continental polar air mass. When air masses of differing properties come into contact in the middle latitudes, they frequently generate storm fronts.

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Etymology

Origin of air mass

First recorded in 1890–95

Example Sentences

"At altitude, high pressure systems exert pressure on this warm air mass, and when we compress a warm air mass, we actually make it even hotter."

From Barron's • Jun. 23, 2026

The Meteo-France weather service said that "the arrival of a slightly cooler air mass" would bring down temperatures on Saturday night.

From Barron's • May 30, 2026

Since 1990, meltwater output during these episodes has risen by 25% compared to the 1950-1975 period when examining cases with similar anticyclonic and cyclonic air mass circulation.

From Science Daily • May 4, 2026

The contrast between this extremely cold air mass and much milder air further south is going to "supercharge" the jet stream.

From BBC • Jan. 20, 2025

Hubbard began to explain that a tropical air mass was moving in from— Groves cut Hubbard off.

From "Bomb" by Steve Sheinkin