Rainfall is a natural process it consists few steps first step includes Nucleation during which water collects on condensation nuclei and forms tiny cloud drops this type of nucleation’s occurs in the tropics. In the second stage the crystal droplet continues to grow in size through condensation. If the drops of crystal grow large enough they start falling.
The amount of rainfall depends on the moisture content in the air. Which depends on three main factors the first includes land and sea contrast. More rainfall occurs along coastal regions since the source of water vapor, the sea is closer than in the interior of continents. The second factor is the direction of the prevailing winds on shore winds from the sea bring more rainfall than wind blowing from the land.
Presence of rainfall also effects the rainfall when mountain obstruct moist winds they are forced to give the rain on the side of the mountain facing the wind, known as the windward side. The side of the mountain facing away from the wind, known as the leeward side, remains dry. The leeward side of the mountain also known as the rain-shadow since it receives very little or no rain.
Beside these facts the vacuum cyclone or the meeting of warm and cold air masses are the causes of the rainfall. Based on these causes there are three types of rainfall. Convectional, relief or orographic and cyclonic or frontal rainfall.