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Question
In your notebook, draw neat, labelled, coloured sketches of the three different types of rainfall. Alongside each diagram, briefly describe in your own words, how each type of rainfall occurs.
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Solution
(a) Convectional Rainfall: In regions closer to the equator, the rate of evaporation is very high. Air gets heated because of the high temperature and starts rising in the form of convection currents. As it rises, it expands and cools. The cooling causes condensation, which results in heavy downpours. This rain is accompanied by thunder and lightning and since it mostly occurs around 4 p.m., it is often called the 4 o’clock showers’.
(b) Relief or Orographic Rainfall: Sometimes moisture-bearing winds are forced to rise because of the presence of a physical barrier, such as a mountain, in their path. Such winds expand and cool as they rise up the slope of the mountain or plateau, and on further cooling form clouds. When saturated, these clouds give rain
(c) Cyclonic or Frontal Rainfall - This type of rainfall occurs when warm and cold air masses meet and form a front. As cold air is denser, it remains close to the ground, while the warm air rises above it. As the warm air rises, it expands and cools, and the moisture in it condenses to form clouds. These clouds bring rainfall.
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