Explain the importance of the Himalayas and the Indian Ocean with respect to the climate of India.

Answer: The Himalayas and the Indian Ocean are the two great controls of the climate of India.

The Himalayas:

• They stop the very cold winds of Central Asia from entering India, so the north Indian plains do not have very severe winters.
• They obstruct the south-west monsoon winds and force them to rise, causing heavy rainfall on their southern slopes and over the northern plains; Ladakh and Tibet remain dry (rain-shadow).
• Because the monsoon winds are held back by the Himalayas, rainfall extends over the whole of north India.
• Their snow and glaciers feed the Indus, Ganga and Brahmaputra, which are perennial.

The Indian Ocean:

• In summer the Indian landmass gets intensely heated and a low-pressure area develops over it (especially over north-west India), while the pressure over the Indian Ocean is relatively high. Hence moisture-laden south-west monsoon winds blow from the ocean towards the land and bring most of India's rainfall.
• In winter the land cools and high pressure forms over it, while pressure over the ocean is lower, so the dry north-east winds blow from land to sea; they pick up moisture over the Bay of Bengal and give rain to the Tamil Nadu coast.
• It moderates the temperature of the coastal and peninsular parts, so the range of temperature there is small.
• Tropical cyclones form over the Bay of Bengal and the Arabian Sea and affect the east and west coasts.