The Kashmir region receives additional amount of precipitation during the winter brought by
- (a)South-west Monsoon
- (b)Western Disturbances
- (c)Retreating Monsoon
- (d)Temperate Cyclone
Correct — B, Western Disturbances. A western disturbance is an extratropical storm that forms over the Mediterranean region, picks up moisture from the Mediterranean, Black and Caspian seas, and is steered eastward by the subtropical westerly jet stream into north-western India. Four or five arrive in an average winter. When one runs into the Himalayan wall it is forced to rise and unloads its moisture, which is why Kashmir, Himachal Pradesh, Punjab, Haryana and western Uttar Pradesh get rain and mountain snow in December, January and February, in a season when the rest of India is dry. This winter rain is what fills the rabi crop's needs and builds the snowpack that feeds the Indus system in summer.
- (a)South-west Monsoon — The south-west monsoon is a summer system, blowing roughly from June to September, and it weakens sharply by the time it reaches the north-west. It cannot be the source of a winter rainfall.
- (c)Retreating Monsoon — The retreating or north-east monsoon of October to December brings rain to the Coromandel coast — Tamil Nadu and coastal Andhra Pradesh — as the winds pick up moisture crossing the Bay of Bengal. It does not water Kashmir.
- (d)Temperate Cyclone — This is the near-miss, because a western disturbance is indeed a temperate or extratropical cyclone by type. But the question wants the name Indian meteorology actually uses for the systems that reach Kashmir, and in the Indian syllabus that name is western disturbance.
India's rainfall comes from three distinct machines. The south-west monsoon of June to September brings most of the annual total to most of the country. The retreating or north-east monsoon of October to December waters the south-eastern coast. Western disturbances of December to March bring the north-west its winter precipitation. Each has its own season, its own source of moisture and its own beneficiary region, and NDA tests the pairing.
The word to seize in the stem is 'winter', which immediately rules out the two monsoon options. Between the two that remain, remember that Indian textbooks and the India Meteorological Department both use the term western disturbance for these systems, so it is the expected answer even though the type is temperate cyclone. The practical importance is large: this rain is what the rabi wheat crop of Punjab and Haryana depends on, a weak western-disturbance season shows up directly in wheat yields, and the same storms are behind much of the avalanche and cloudburst risk in the western Himalaya.
- Western disturbances are extratropical storms that originate near the Mediterranean and travel east on the subtropical westerly jet.
- About four or five reach north-west India in an average winter, mostly between December and March.
- They deliver winter rain and Himalayan snow to Kashmir, Himachal Pradesh, Punjab, Haryana and western Uttar Pradesh.
- This winter precipitation is decisive for the rabi crop, above all wheat.
- The retreating or north-east monsoon, by contrast, waters Tamil Nadu and the Coromandel coast in October to December.
- Choosing 'temperate cyclone' because it is technically the storm type; the syllabus term is western disturbance.
- Assuming all Indian rainfall comes from a monsoon.
- Confusing the retreating monsoon, which serves the south-east coast, with the winter rain of the north-west.
NDA pairs a season and a region with the system that waters it, and has also asked which crop the western-disturbance rain benefits.
Which one of the following crops is generally benefitted by the rain caused by western disturbances in India ?
- (a) Rice
- (b) Wheat
- (c) Bajra
- (d) Cotton
Answer(b) Wheat
Takes the same system one step further, to what the winter rain is actually good for, which is the form NDA has favoured more recently.
- practice — not a real PYQ
Winter rainfall from western disturbances is most important for which crop?
- (a)Wheat
- (b)Rice
- (c)Bajra
- (d)Cotton
Answer(a) Wheat — the main rabi crop of Punjab, Haryana and western Uttar Pradesh, sown in winter and dependent on this rain.
- practice — not a real PYQ
The rainfall of Tamil Nadu in October to December comes mainly from
- (a)the retreating or north-east monsoon
- (b)western disturbances
- (c)the south-west monsoon
- (d)convectional thunderstorms of summer
Answer(a) the retreating or north-east monsoon — winds crossing the Bay of Bengal pick up moisture and shed it on the Coromandel coast.