Ans.

Mountain or Orographic or Relief Rainfall: – When a high mountain comes in the path of steamy winds, the air is forced to rise.  The slope of the mountain from which the wind rises is called the windward slope and the slope opposite to it is called the leeward slope.  Due to rising, this air cools down and becomes saturated, as a result, its water vapor condenses and turns into clouds, so this air rains heavily on the windward slope, it is called mountain or surface rain.  When these winds descend on the windward slope, they become hot and dry, due to which there is no rain.  Therefore, the wind-facing slope is called the rain shadow area.  A good example of mountain rainfall is the western coastal plain of India.  The south-west monsoon winds coming from the Arabian Sea collide with the Western Ghats and cause 600 cm of rain in Mahabaleshwar, located on the windward slope, whereas in Poona, located in the rain shadow region, only 70 cm of rainfall is received from these winds.  Other examples of rain shadow regions are the Shillong plateau in India and the Tibetan plateau in China.