The winter rains caused Western disturbance North Western Plain of India gradually decreases from

Western disturbances are eastward-moving extratropical cyclonic systems that originate over the Mediterranean and Caspian region and bring winter rain and snow to northwest India. Their moisture and intensity are greatest in the northwest and weaken as they travel east, so winter rainfall over the North Western Plains decreases from West to East. Punjab, Haryana and western Uttar Pradesh get noticeably more winter rain than the eastern Gangetic plain.

Why the other options fail:

• A (East to West): This is the reverse of the pattern. Winter rain actually increases towards the west.
• C (North to South) and D (South to North): Western disturbance rainfall in the plains is governed by longitude (distance from the source region), not latitude. The north-south comparison has no basis in this pattern.

Core concept: western disturbances, their winter rainfall gradient and their role in rabi crops such as wheat. For Mains, link this to the Himalayan snowfall and glacier mass balance, and to the effect of weakening western disturbances on wheat yields.

Trap: Aspirants mix this up with the monsoon, where rainfall in the plains decreases from east to west (Bengal to Punjab). Western disturbance rain runs in the opposite direction, so check which system the question is about.