What is Absolute Humidity?

Absolute Humidity:

Absolute humidity is the mass of water vapor, , per unit volume of total air and water vapor mixture, , which can be expressed as:

Absolute humidity in the atmosphere ranges from near zero to roughly 30 grams per cubic meter when the air is saturated at 30 °C.
The absolute humidity changes as air temperature or pressure changes. This makes it unsuitable for chemical engineering calculations, e.g. for clothes dryers, where temperature can vary considerably. As a result, absolute humidity in chemical engineering may refer to mass of water vapor per unit mass of dry air, also known as the mass mixing ratio, which is better suited for heat and mass balance calculations. Mass of water per unit volume as in the equation above is also defined as volumetric humidity.
In short, the total amount of water vapour present in a given volume of air. It does not take temperature into consideration.
The field concerned with the study of physical and thermodynamic properties of gas–vapor mixtures is named psychrometrics.