Humidity

Humidity is the measure of the amount of water vapor present in the atmosphere (or generally in an air mass).
Relative humidity, in particular, indicates the percentage ratio between the amount of vapor contained by an air mass and the maximum amount (i.e., at saturation) that the air volume can contain under the same temperature and pressure conditions. At the dew point temperature, relative humidity is by definition 100%. Relative humidity is a parameter given by the ratio between absolute humidity and saturation humidity. It is independent of temperature and gives an idea of the saturation rate of atmospheric vapor, and the repercussions on evapotranspiration phenomena of crops. The saturation deficit is given by the difference between absolute humidity and saturation humidity.