Air and humidity

Depending on the temperature, air may contain a certain quantity of water vapour (expressed in grams of water vapour per kilogram of air). The maximum quantity of water vapour that air can contain at a given temperature is called the saturation humidity (SH). The actual quantity of water vapour that the air contains is called the absolute humidity (AH). The ratio of these two values ​​is called the relative humidity (RH). If the RH at a given temperature is 80%, this therefore means that the air contains 80% of the quantity of water vapour that it could contain at that temperature.

The humidity deficit (HD) is the difference between the maximum quantity of humidity that the air can contain and the actual quantity of humidity in the air. The humidity deficit is expressed in g/m³.