The wind filled with moisture from the sea enters into the land. Gradually, it moves upwards through the mountain slopes and cools down there. After condensing it led to the formation of clouds.

The windward side as shown in the figure receives heavy rainfall whereas the other side or the leeward side does not receive rainfall. It is because on the leeward side the dry air is descending. The leeward side which does not receive rainfall is also known as rain shadow regions. This type of rainfall is known as orographic rainfall or relief rainfall.