With reference to “water vapour”, which of the following statements is/are correct?
- It is a gas, the amount of which decreases with altitude.
- Its percentage is maximum at the poles.
Select the answer using the code given below:
- 1 only
- 2 only
- Both 1 and 2
- Neither 1 nor 2
Explanation
Statement 1 is correct
- Water Vapour is one of the most variable gaseous substances present in the atmosphere, constituting between 0.02% and 4% of the total volume (in cold, dry, and humid tropical climates, respectively). 90% of the moisture content in the atmosphere exists within 6 km of the surface of the Earth. Like carbon dioxide, water vapour plays a significant role in the atmosphere’s insulating effect. It absorbs not only the long-wave terrestrial radiation (infrared, or heat emitted by the earth at night) but also part of the incoming short-wave solar radiation (visible and UV). Its concentration decreases with altitude because the atmosphere becomes thinner and cooler.
Statement 2 is incorrect
- It is maximum in equatorial and tropical regions, where temperatures and evaporation rates are high.
