Question

Give reasons as to why: Seasonal reversal of wind direction takes place over the Indian subcontinent?

Answer 1

• Over Indian subcontinent, the wind and pressure conditions are unique.
• In the north of the Himalayas, there is a high-pressure area, during winter.
• In the South, over the oceans, there are areas with low pressure, hence the dry and cold winds will blow from North to the low pressure areas.
• Over northwestern India and the interior of Asia, there will be areas with low pressure during summer.
• Hence during summer there will be total reversal in the direction of wind movement.
• Over the Southern Indian ocean, the air will start moving from high pressure areas towards the south easterly direction, once it crosses, these winds will move towards the Indian subcontinent which has low-pressure areas.
• Southwest monsoon winds are the name given to these winds blowing from the ocean.
• These winds bring widespread rainfall over India, as they pick up moisture while blowing over the warm oceans.
• From early June to mid-September, around 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.
• Central part of the country and Saurashtra-Kachchh region receives the Arabian sea branch of the monsoon by mid of June.
• 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 process of retreat or withdrawal of monsoon is a very gradual process.
• By early September, monsoon starts to withdraw from the Northwestern states of India.
• From the northern half of the peninsula, the withdrawal of monsoon will be completed by mid-october.
• The withdrawal of monsoon is rapid from the Southern half of the Peninsula.
• The withdrawal is completed from the rest of the country by early December.