absolute humidity

n.
The amount of water vapor present in a unit volume of air, usually expressed in kilograms per cubic meter.

The density of the water vapour present in a mixture of air and water vapour, that is, the ratio of the mass of water vapour to the volume occupied by the mixture, usually measured in grams per cubic centimetre. Cold air cannot contain as much water vapour as warm air, so cold air has a lower absolute humidity than warm air. See also relative humidity.

The mass of water vapor per unit volume of air.

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n.

The weight of water vapor present per unit volume of a gas or a mixture of gases.