Question

Give reasons as to why: The bulk of rainfall in India is concentrated over a few months.

Answer 1

• By early June, the low-pressure condition over the northern plains intensifies. It attracts the trade winds of the Southern hemisphere. Warm subtropical areas of the southern oceans are the place where these south-east trade winds originate.
• These winds bring rain in India. They bring abundant moisture to the subcontinent, as these winds blow over warm oceans.
• These trade winds enter India as South west monsoon, they blow with an average velocity of 30 Km/hr.
• From early June to mid-September, between 100- 120 days is the duration of the monsoon. Some places like Tamil Nadu receive a major portion of its rainfall during October and November, but most parts of the country receive rainfall from June to September.
• Generally by the first week of June, the monsoon arrives at the southern tip of the Indian peninsula.
• Later the Monsoon splits into two branches – the Bay of Bengal branch and the Arabian Sea branch.
• The Bay of Bengal branch arrives in Assam by the first week of June.
• Mumbai receives the Arabian sea branch around 10th June.
• Central part of the country and Saurashtra-Kachchh region receives the Arabian sea branch of the monsoon by mid of June.
• The Bay of Bengal branch of the monsoon reaches Delhi by the end of June.
• Over the northwestern part of the Ganga plains, the Bay of Bengal branch and Arabian Sea branch of the monsoon merge.
• Eastern Rajasthan, Haryana, Punjab, Western Uttar Pradesh receives the monsoon by the first week of July.
• The monsoon reaches the rest of the country, including Himachal Pradesh by mid-July.
• The annual precipitation is less than 10 cm in Western Rajasthan and Ladakh, whereas in Meghalaya the annual precipitation is over 400 cm.
• In the Northern plains, there is generally a decrease in rainfall from East to West.