(i) The average annual rainfall of India is 110 cm. Regional variations in the distribution are found due to differences in relief of the country. Rainfall is unevenly distributed throughout the country. India can be divided into the following rainfall regions: Areas of heavy rainfall: These areas get more than 200 cm, of annual rainfall. These include Western Coast and Western Ghats, Sub-Himalayas, and the North-east parts of India. Areas of moderate rainfall: These areas get annual rainfall of 100-200 cm. These include West: Bengal, Orissa, Bihar, Eastern parts of U.P., and Madhya Pradesh; coastal plains of Tamil Nadu. Areas of very little rain: Jammu-Kashmir, Western Rajasthan (Thar Desert). (ii) The Western Ghats: places to the windward side of the Ghats, e.g., Mumbai, Goa, Mangalore, Kerala coast get heavy rain, Places on the leeward side like Pune, the Deccan plateau, Chennai, get less rain. Garo-Khasi Hills: Cherrapunji which is favourably situated in these hills, gets entrapped in the Bay of Bengal branch of the S.W. Monsoon and gets very heavy rain, Shillong which lies on the leeward side of these Hills gets less rain. Aravalli Hills: These hills run parallel to the Arabian Sea branch of the S.W. Monsoon and is not conducive to rain. Besides, the Bay of Bengal winds of the S.W. Monsoon coming from the east is blocked and hence Rajasthan lying on the leeward side of these Hills, gets little rain. This is why Thar is a desert. The Himalaya Mountains block the Bay of Bengal branch of the S.W. Monsoon from crossing the mountains. The places on the southern slopes of the Mountains get heavy rain.