Retreat of Indian Monsoon – Indian Geography Series – Free PDF

Retreating Monsoon  and  The North-East Monsoon

• The months of August and September mark the reduction and cessation of the rainfall by the southwest monsoon.
• The low-pressure trough that was built in the northwest part of India starts to disintegrate and there is an eventual shift to the equatorial region towards the end of September.
• The low pressure zone formed gets weakened because of two reasons:

1. The apparent movement of the Sun towards the equator
2. The lowering of the temperature due to the monsoonal rains.

• Till the September equinox(23r Sept.), the STHPB starts moving towards the 30°N latitude region.
• The anti-cyclonic condition starts prevailing over the cyclonic conditions.
• The ITCZ also recedes south of the equator.
• The conditions continue from October till mid-December and are regarded as the retreating monsoon.
• The monsoon winds follow the last reach first withdraw pattern.

Winter Season

• By the winter solstice in December(22nd December), the sun vertically shines over the tropic of Capricorn.
• The low temperatures average around 20°celcius, which runs as an isotherm across the tropic of cancer.
• The reasons for excessive cold during this season are:

1. The northern plains are far from the moderating effect of the sea.
2. The cold wave snowfall in the nearby Himalayan ranges reduces the temperature drastically.
3. Western Disturbances originating around the Mediterranean.

• The Peninsular region of India does not have any well-defined cold-weather season because of the moderating influence of the sea and its proximity to the equator.
• The subtropical jet streams play an important role in guiding these disturbances towards the Indian subcontinent.

Indian Geography (Fundamental) | Free PDF

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