question_answer 8)

Give reasons as to why    (i) Seasonal reversal of wind direction takes place over the Indian subcontinent.   (ii) The bulk of rainfall in India is concentrated over a few months.   (iii) The Tamil Nadu coast receives winter rainfall.   (iv) The delta region of the eastern coast is frequently struck by cyclones.   (v) Parts of Rajasthan, Gujarat and the leeward side of the Western Ghats are drought prone.  

Answer:

(i) During winter, there is a high pressure area north of the Himalayas.Cold winds blow from this region to the low pressure areas over the oceans to the south.   (a) In summer, a low pressure area develops over interior Asia as well as over north-western India.   (b) This causes a complete reversal of the direction of winds during summer. (ii) In summer, a low pressure area develops over interior Asia as well as over north western India.  (a) This causes a complete reversal of the direction of winds during summer. Air moves from the high pressure area over the southern Indian ocean, crosses the equator and turns right towards the low pressure areas over the Indian subcontinent.   (b) These are known as the south-west monsoon winds.   (c) These winds blow over warm oceans, gather moisture and bring widespread rainfall over the mainland of India.   (d) The duration of the monsoon is between 100-120 days from early June to mid September. Thus, we can say that rainfall in India is concentrated over a few months. (iii) During the winter season, the north-west trade winds prevail over the country. They blow from land to sea and hence for most part of the country it is a dry season. Some amount of rainfall occurs on the Tamil Nadu coast from these winds as here they blow from sea to land. (iv) The delta region of the eastern coast is frequently struck by cyclones because the cyclonic depressions which originate over the Andaman Sea generally cross the Eastern coasts of India and cause heavy and widespread rain,   (a) These cyclones are often very destructive. The thickly populated deltas of the Godavari, the Krishna and the Kaveri are frequently struck by cyclones which cause great damage to life and property.   (b) Sometimes these cyclones arrive at the coasts of Odisha, West Bangal and Bangladesh. (v) Parts of Rajasthan, Gujarat and the leeward side of the Western Ghats are drought prone because they receive scanty rainfall. Even during the monsoon months the monsoon winds when rising over the Western Ghats give rain to that area. By the time they reach Rajasthan and Gujarat there is very less moisture left in these winds and so these areas are drought prone.