• During winter, a high pressure area develops north of the Himalayas.
• Cold dry winds blow from this region to the low pressure areas over the oceans to the south.
• In summer, a low pressure area develops over interior Asia as well as over northwestern India.
• This causes a complete reversal of the direction of winds during summer.
• Air moves from the high pressure area over the southern Indian ocean in a south-westerly direction, crosses the equator and turns right towards the low pressure area over the Indian sub-continent.
• These winds are known as south-west monsoon winds.
• These winds blow over the warm oceans, gather moisture and bring widespread rainfall over the mainland of India.