Important Factors of Climate of India
The following factors affect the climate of India very profoundly.
Latitude? Tropic of Cancer passes through the middle of the country from the Rann of Kuchchh in the west of Mizoram in the east.
It divides India almost in two equal parts.
(a) The portion lying south of Tropic of Cancer, lies in tropical zone.
(b) The portion in north of Tropic of Cancer lies in the subtropics. Hence, India’s climate has traits of tropical as well as subtropical climates.
Temperatures remain high’ throughout the year in South India while they are high in summer and low in winter.
India has mountains to its north, with the highest peaks rising above 8,000 metres above mean sea level.
India has a vast coastal area with maximum elevation of about 30 metres.
(а) The Himalayas prevent the cold winds during winter from Central Asia from entering the subcontinent. The result is that the subcontinent experiences comparatively milder winters.
(b) Temperature differences are minimum between the tropical and subtropical India.
The following atmospheric conditions govern the climate and associated weather; conditions prevalent in India:
i. Air pressure and surface winds.
ii. Upper air circulation.
iii. Western disturbances and tropical cyclones.
Air Pressure and Surface Winds:
From the above map, it is noticed that.
India lays in the region of North-East Trades winds.
These winds originate from the subtropical high-pressure belt of the Northern Hemisphere.
They blow south, get deflected to the right due to the Coriolis force, and move on towards the equatorial low pressure area.
These winds carry very little moisture as they originate and blow over land. Hence they cause almost no rain. Thus, India should have been an arid land, but it is not so. The following account reveals the reason for this:
- Pressure and wind conditions over India are unique.
- •During winter high-pressure area prevails north of the Himalayas.
Cold dry winds blow from this region to the low-pressure areas over the oceans in the south.
During summer a low-pressure area develops over Central Asia as well as over the regions surrounding the^ Arabian Sea.
i. It includes north-western India.
ii. This causes a complete reversal of winds during summer.
iii. Air moves from the high-pressure area over the southern Indian Ocean.
a. Here it moves in a south-easterly direction.
b. After crossing equator it turns right towards the low-pressure areas over the Indian subcontinent.
c. It is known as the South-west Monsoon winds.
d. These winds blow over the warm oceans and gather moisture. Hence they bring widespread rainfall over India.
Upper Air Circulation:
For Jet stream please study the answer of No. 16, page 257. Western Disturbances and Tropical Cyclones Western Disturbances
- Western disturbances are weather phenomenon of the winter months.
- They are brought in India by the westerly flow.
- They are usually located in the North and North-western India.
Tropical cyclones are also called tropical depressions. They occur during Monsoon as well as in October-November.
- They are actually part of the easterly flow.
- They originate on the Bay of Bengal. Easterly flow boosts them into Indian subcontinent and cause rainfall over eastern coasts.