Answer the following questions in about 30 words.

(i) Name the three types of precipitation.


(ii) Explain relative humidity.


(iii) Why does the amount of water vapour decreases rapidly with altitude?


(iv) How are clouds formed? Classify them.


(i) The three types of precipitation are:

• Rainfall: Precipitation in the form of water.


• Sleet: Frozen rainfall


• Hailstones: Solid pieces of ice which reach the surface.


(ii) The atmosphere, at any time, has the capacity to hold a certain amount of water depending on its temperature. If the air holds maximum possible amount of vapour, it is called saturated. However, the percentage of water vapour held by the air, measured against the capacity of saturated air, is called relative humidity.


(iii) The amount of water vapour decreases rapidly with altitude due to the absence of water bodies which are a source of vapour. Also, temperature decreases with increasing height, which reduces the water-holding capacity.


(iv) Clouds are formed by the condensation of water vapour at higher altitudes around dust particles.


They are of the following types:


• Cirrus


• Cumulus


• Stratus



2