Which one of the following causes is responsible for rainfall during winters in north-western part of India?

The correct answer is C) Western disturbances. These are extratropical cyclonic systems that form over the Mediterranean, Caspian and Black Sea region and travel eastward with the subtropical westerly flow. When they reach the Himalayas and north-western plains, they bring winter and early spring rain and snow to Jammu and Kashmir, Himachal Pradesh, Punjab, Haryana, Uttarakhand, western UP and parts of Rajasthan. This rain is vital for rabi crops such as wheat.

• A) Retreating monsoon: The north-east (retreating) monsoon, active from October to December, mainly affects Tamil Nadu, coastal Andhra Pradesh and south-east peninsula. It does not drive winter rain in the north-west.
• B) Cyclonic depression: Tropical depressions and cyclones form over the Bay of Bengal and Arabian Sea and affect the coasts and peninsula, mostly in the monsoon and post-monsoon seasons. Western disturbances are extratropical, not tropical, and they are the real winter driver here.
• D) South-West monsoon: The summer monsoon arrives in June and withdraws from north-west India by mid-September, so it has no role in winter rainfall.

The core concept is the winter circulation pattern over India. For Mains (GS-1 Geography and GS-3 Agriculture/Water), remember that western disturbances link to rabi productivity, Himalayan snowfall, glacier mass balance and winter fog and cold waves.

Trap: Many aspirants pick the retreating monsoon because it is the only "winter" rain they associate with India. Remember that it is a peninsular and south-east phenomenon.