Indian Geography Part 10 – The Seasons & Rainfall


The Hot Weather Season (summer)

  • Due to the apparent northward movement of the sun, the global heat belt shifts northward.

  • In March, the highest temperature is about 38° Celsius, recorded on the Deccan plateau.

  • In April, temperatures in Gujarat and Madhya Pradesh are around 42° Celsius.

  • In May, temperature of 45° Celsius is common in the north-western parts of the country

  • In peninsular India, temperatures remain lower due to the moderating influence of the oceans.

‘Loo’

These are strong, gusty, hot, dry winds blowing during the day over the north and north-western India.

  • Sometimes they even continue until late in the evening

  • Direct exposure to these winds may even prove to be fatal

 

‘Kaal Baisakhi’

 In West Bengal, these storms are known as the ‘Kaal Baisakhi’ calamity for the month of Baisakh

 Advancing Monsoon (The Rainy Season)

  • By early June, the low-pressure condition over the northern plains intensifies.

  • It attracts the trade winds of the southern hemisphere.

  • These south-east trade winds originate over the warm subtropical areas of the southern oceans. They cross the equator

  • Blow in a south-westerly direction entering the Indian peninsula as the south-west monsoon.

  • As these winds blow over warm oceans, they bring abundant moisture to the subcontinent.

  • These winds are strong and blow at an average velocity of 30 km per hour.

  • Early in the season, the windward side of the Western Ghats receives very heavy rainfall, more than 250 cm

  • The Deccan Plateau and parts of Madhya Pradesh also receive some amount of rain in spite of lying in the rain shadow area.

  • The maximum rainfall of this season is received in the north-eastern part of the country.

  • Mawsynram in the southern ranges of the Khasi Hills receives the highest average rainfall in the world.

  • Rainfall in the Ganga valley decreases from the east to the west.

  • Rajasthan and parts of Gujarat get scanty rainfall.

  • Phenomenon associated with the monsoon is its tendency to have ‘breaks’ in rainfall.

  • It has wet and dry spells.

  • The monsoon rains take place only for a few days at a time.

  • These breaks in monsoon are related to the movement of the monsoon trough.

  • The trough and its axis keep on moving northward or southward

  • When the axis of the monsoon trough lies over the plains, rainfall is good in these parts

  • Whenever the axis shifts closer to the Himalayas, there are longer dry spells in the plains,

  • Widespread rain occur in the mountainous catchment areas of the Himalayan Rivers.

  • These heavy rain bring in their wake, devastating floods causing damage to life and property in the plains.

  • The frequency and intensity of tropical depressions too, determine the amount and duration of monsoon rains.

  • These depressions form at the head of the Bay of Bengal and cross over to the mainland.

  • The depressions follow the axis of the “monsoon trough of low pressure”.

  • The monsoon is known for its uncertainties.

  • The alternation of dry and wet spells vary in intensity, frequency and duration.

 

Retreating Monsoon (The Transition Season)

  • During October-November, with the apparent movement of the sun towards the south,

  • The monsoon trough or the low-pressure trough over the northern plains becomes weaker.

  • Gradually replaced by a high-pressure system.

  • The south-west monsoon winds weaken and start withdrawing gradually

  • By the beginning of October, the monsoon withdraws from the Northern Plains.

  • The months of October-November form a period of transition from hot rainy season to dry winter conditions.

  • Mawsynram, the wettest place on the earth is also reputed for its stalagmite and stalactite caves.

Cyclonic depressions

  • The low-pressure conditions, over north-western India

  • Get transferred to the Bay of Bengal by early November.

  • This shift is associated with the occurrence of cyclonic depressions,

  • Which originate over the Andaman Sea.

  • These cyclones generally cross the eastern coasts of India cause heavy and widespread rain.

  • These tropical cyclones are often very destructive.

  • Deltas of the Godavari, the Krishna and the Kaveri are frequently struck by cyclones, which cause great damage to life and property.

DISTRIBUTION OF RAINFALL

  • The western coast and north-eastern India receive over about 400 cm of rainfall annually.

  • It is less than 60 cm in western Rajasthan and adjoining parts of Gujarat, Haryana and Punjab.

  • Rainfall is equally low in the interior of the Deccan plateau, and east of the Sahyadris

  • A third area of low precipitation is around Leh in Jammu and Kashmir

  • The rest of the country receives moderate rainfall, snowfall is restricted to Himalayan region

Access Full  E-Book Here


Related Post

Share this

Leave a Reply

Your email address will not be published. Required fields are marked *