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

Instead of coming from the east, the winds will come from the ocean and provide a cooler air mass, he said.

From Los Angeles Times • Feb. 9, 2026

The storm was expected to linger for days, shifting into the heavily populated mid-Atlantic and northeastern states while crippling daily life and ushering in a frigid air mass across the country.

From Barron's • Jan. 23, 2026

The extreme weather, part of a bitterly cold air mass that has descended on the south and eastern US, is forecast to linger over the next couple of days.

From BBC • Jan. 21, 2025

Video, 00:02:23How does air mass influence our weather?

From BBC • Sep. 12, 2024

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

From "Bomb" by Steve Sheinkin