The percentage composition of water vapour in the air, by volume, varies from 0.4% to 4%.
Significance of water vapour in the air
The amount of water present in the air affects climatic conditions. Excessive water vapor causes rain. Water vapor is also responsible for fog, mist, and hail.
The presence of water vapour in the air is very important for the health and comfort of animals. Excess of, as well as deficiency of, water vapour in air causes health-related problems.
Presence of water vapour affects the rate of evaporation of water from plants and animals.
Water vapour in the air is essential for the growth of plants.