Question

North-Western parts of India get winter rainfall mainly due to _________________
A. North-West monsoon
B. Western disturbances
C. North-East monsoon
D. Retreating monsoon

Answer 1

Hint: In the Coromandel Coast, winter rainfall is instigated due to the North East Monsoon airstreams. When these air streams waft over the Bay of Bengal, they gather up dampness and bring precipitation in the coastal areas of Andhra Pradesh and Tamil Nadu.

Complete answer:
Western disturbances instigate in the Mediterranean area. A high-pressure zone over Ukraine and the surrounding area combines, producing the imposition of cold air from polar areas towards an expanse of moderately warmer air with high humidity. This produces positive circumstances for cyclogenesis in the upper atmosphere, which endorses the creation of an eastward-moving extra tropical dip. Roaming at rapidity up to 12 m/s (43 km/h; 27 mph), the uproar travels towards the Indian subcontinent until the Himalayas hinders its growth, upon which the dip quickly deteriorates. The western disturbances are entrenched in the mid-latitude subtropical westbound jet stream. Western disturbances, precisely the ones in winter; bring restrained to heavy rain in low-lying expanses and heavy snow to hilly expanses of the Indian Subcontinent. They are the source of most winter and post-monsoon season precipitation across northwest India. Rainfall throughout the winter season has huge significance in agriculture, predominantly for the rabi crops.

Thus, option (B) is correct.

Note: Western disturbances begin deteriorating in numbers after winter. Throughout the summer months of April and May, they interchange across north India. The southwest monsoon current usually marches from east to west in the northern Himalayan area, contrasting western disturbances which trail west to east drift in north India with a consequential increase in pressure bearing cold pool of air. This aids at the beginning of the monsoon in some portions of northwest India. It also instigates pre monsoon rainfall, particularly in northern India.