Consider the following statements regarding water vapour:

1. In the warm and wet tropics, it may account for 100 per cent of the air by volume.

2. It is not a greenhouse gas.

Which of the statements given above is/are correct?

Water vapour is a variable gas in the atmosphere, which decreases with altitude. In the warm and wet tropics, it may account for four per cent of the air by volume, while in the dry and cold areas of desert and Polar Regions; it may be less than one per cent of the air. Water vapour also decreases from the equator towards the poles.

Water vapour also absorbs parts of the insolation from the Sun and preserves the Earth’s radiated heat. It thus, acts like a greenhouse gas, allowing the Earth neither to become too cold nor too hot. Water vapour also contributes to the stability and instability in the air.