4. Humidity

Humidity refers to the amount of water vapour present in the atmosphere at a particular time and place. Humidity in the air is due to the various processes of evaporation from the land and water surfaces of the Earth. It can be expressed as an absolute, specific or a relative value.

4.1. Absolute Humidity 4.2. Specific Humidity 4.3. Relative Humidity 4.3.1. Significance of Relative Humidity 4.3.2. The Horizontal Distribution of Relative Humidity