World Geography / Climatology
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There are three types of rainfall around the world namely, Orographic rainfall, Convectional rainfall and Frontal or Cyclonic rainfall. These forms of precipitation or rainfall happens mainly due to the warm era. Rainfall occurs when winds carrying moisture rise up and expansion (adiabatic) takes place and hence cools which in turn results in condensation. If winds are descending, there will be compression of the winds which results in heating and the winds start absorbing the moisture. Descending winds never cause rainfall.
The different types of rainfall in the world are given below
Relief or Orographic rainfall occurs when there is obstruction to the wind flow. Saturated warm and humid winds, when
obstructed by a mountain or tableland, rise along with the slope of the mountain. When they rise, there is huge amount of rainfall on
the windward side.
After crossing the mountain, they descend downwards where there will be less rainfall in the leeward side. As an example, the
rainfall in the Western Ghats is 200 cm on the windward
side whereas on the leeward side (rain shadow region), it is 50-60 cm.
Convectional rainfall is very common in Equatorial region. In Equatorial region, temperature is high and winds move up. When they
reach some height, they get cooled down and cause heavy rainfall.
Convection currents are there throughout the year (as temperature is high) and hence there will be rainfall throughout the year. In the
Equatorial region, 300 out of 365 days are rainy days. There will be rain everyday from 3.30PM to 4PM.
Frontal or Cyclonic rainfall are the intense form of weather disturbances. They are associated with very high rainfall. Of the three types of rainfall, this type occurs only in the coastal regions.