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

La Niña seasons typically produce large numbers of atmospheric rivers, or narrow bands of concentrated water vapor in the sky that act like rivers in the sky.

From Salon

This means the reactor needs to interact with water vapor.

From Science Daily

Firstly, water vapor interferes and overlaps with the absorption spectra of many gases in the standard infrared ranges normally used for detection.

From Science Daily

Globally, freshwater levels have stayed consistently low since the 2014-2016 El Niño, while more water remains trapped in the atmosphere as water vapor.

From Science Daily

Higher temperatures enhance the atmosphere’s capacity to hold water vapor, increasing the quantities of moisture evaporating off the landscape.

From Los Angeles Times