water vapor

noun

1. a dispersion, in air, of molecules of water, especially as produced by evaporation at ambient temperatures rather than by boiling. Compare steam ( def 2 ).

water vapor

1. Water in its gaseous state, especially in the atmosphere and at a temperature below the boiling point. Water vapor in the atmosphere serves as the raw material for cloud and rain formation. It also helps regulate the Earth's temperature by reflecting and scattering radiation from the Sun and by absorbing the Earth's infrared radiation.
2. See also vapor

Word History and Origins

Origin of water vapor¹

First recorded in 1875–80

Example Sentences

Instead, they are what happen when water vapor turns straight into ice.

From Science News For Students

That’s because, in both cases, the addition of abundant aerosol particles to the atmosphere gives water vapor numerous surfaces on which to condense, creating many small water droplets that form this brighter cloud and reflect incoming radiation.

From Science News

All three meteorites mostly let off water vapor, which accounted for 62 percent of the gas emitted on average.

From Science News

Air contains lots of different gases, including water vapor.

From Science News For Students

For those of you who did not spend any part of your lives near a Great Lake, lake-effect snow is a weather phenomenon in which cold winds blow across large bodies of warmer water, picking up water vapor from the surface.

From Washington Post

So which influence wins out—increasing water vapor or decreasing wind shear?

From The Daily Beast

That's not including water vapor, of which there is a fair amount.

From Project Gutenberg

The Enterprise had taken damage in the last exchange; Koreff's spectroscopes showed her halo-ed with air and water vapor.

From Project Gutenberg

The next most abundant product of the fermentation is water vapor which can often be seen passing off in clouds of steam.

From Project Gutenberg

In the case just cited, the union of two volumes of hydrogen and one of oxygen results in precisely two volumes of water vapor.

From Project Gutenberg

The presence of some water vapor in the air is absolutely necessary to animal and plant life.

From Project Gutenberg