Which of the following are correct with regard to Indian Monsoonal Rainfall ? 1. Largely governed by the topographical features 2. Regional and seasonal variation in the distribution of rainfall 3. Heavy downpour resulting in considerable runoff 4. Beginning and end of rain is regular and on time Select the correct answer using the code given below :
- (a)1 and 2 only
- (b)1, 2 and 3
- (c)3 and 4 only
- (d)2, 3 and 4
Correct — B, 1, 2 and 3. Statement 1 holds because relief decides where the monsoon unloads: the windward slopes of the Western Ghats and the Meghalaya hills are drenched while the leeward side lies in rain shadow, and the Tamil Nadu coast stays dry in the southwest monsoon because it runs parallel to the Bay of Bengal branch and sits in the rain shadow of the Arabian Sea branch. Statement 2 holds because rainfall varies enormously across the country and across the year — India averages about 125 cm a year, yet Cherrapunji and Mawsynram receive over 1,080 cm while Jaisalmer rarely gets more than 9 cm. Statement 3 holds because monsoon rain arrives in heavy bursts rather than gentle drizzle, so much of it runs off instead of soaking in, and NCERT notes that the sudden burst of the monsoon creates a problem of soil erosion over large areas. Statement 4 is the false one: the onset and withdrawal dates shift from year to year, and in the strong El Niño of 1990-91 the onset was delayed over most of the country by five to twelve days.
- (a)1 and 2 only — It drops statement 3, but the concentration of monsoon rain into heavy downpours is one of its best-documented features and is exactly why so much of it is lost as runoff.
- (c)3 and 4 only — It admits statement 4, which is the one clearly false item — the beginning and end of the rains are notoriously irregular — and it leaves out the topographic control and the variability that everyone accepts.
- (d)2, 3 and 4 — It carries the false statement 4 and drops the true statement 1. Relief is the single biggest control on where monsoon rain actually falls in India.
The Indian monsoon is a seasonal reversal of winds driven by the differential heating of land and sea, reinforced by the Himalayan barrier and the shifting of the inter-tropical convergence zone. The southwest monsoon reaches the mainland around the beginning of June and withdraws through September and October, and it delivers the bulk of the country's annual rainfall in that spell. Its behaviour is uneven in three ways at once — from place to place, from season to season, and from year to year — and the last of these, interannual variability linked partly to El Niño, is what makes Indian agriculture a gamble on the rains.
Statement-based questions on the monsoon usually plant one absolute claim, and the word to hunt for is the one that promises regularity or certainty. Here it is 'regular and on time' in statement 4. The India Meteorological Department publishes normal dates of onset precisely because actual dates depart from them, and both early and late onsets are common. The other three statements are the standard textbook characteristics of monsoon rainfall — topographically controlled, highly variable in space and time, and concentrated in heavy downpours with the erosion and runoff that follow.
- India's average annual rainfall is about 125 cm, but Cherrapunji and Mawsynram in the Khasi Hills exceed 1,080 cm a year while Jaisalmer rarely gets more than 9 cm.
- Mawsynram, on the crest of the Khasi Hills, receives the highest average annual rainfall in the world.
- The Tamil Nadu coast stays dry during the southwest monsoon because it lies parallel to the Bay of Bengal branch and in the rain shadow of the Arabian Sea branch; October and November are its rainiest months.
- The sudden burst of the monsoon delivers rain in heavy spells, causing large-scale runoff and soil erosion.
- Onset and withdrawal dates vary from year to year — a strong El Niño in 1990-91 delayed the onset over most of the country by five to twelve days.
- Accepting a statement that claims the monsoon is regular or dependable — variability is its defining feature.
- Forgetting that eastern Tamil Nadu gets most of its rain from the retreating or northeast monsoon in October and November.
- Treating heavy rainfall totals as high water availability; much of a downpour is lost as runoff.
NDA asks which characteristics of monsoon rainfall are correct, or sets the duration, onset or regional distribution of the monsoon as a one-line question.
High temperature and low pressure over the Indian sub-continent during the summer season, draws air from the Indian Ocean leading to the in-blowing of the
- (a) Southeast monsoon
- (b) Southwest monsoon
- (c) Trade winds
- (d) Westerlies
Answer(b) Southwest monsoon
Supplies the mechanism behind the rainfall whose characteristics this question lists — the land-sea pressure contrast that pulls the moist southwest flow in.
The duration of monsoon in India extends for an average period of
- (a) 80 – 140 days
- (b) 100 – 120 days
- (c) 90 – 130 days
- (d) 100 – 140 days
Answer(b) 100 – 120 days
Puts a number on the season's length, which is the reason the same annual total has to fall in heavy bursts with heavy runoff.
- practice — not a real PYQ
The rainfall of the Coromandel coast of Tamil Nadu is received mainly during
- (a)the southwest monsoon in June and July
- (b)the retreating or northeast monsoon in October and November
- (c)the winter western disturbances
- (d)the pre-monsoon showers of April
Answer(b) the retreating or northeast monsoon in October and November — the coast lies in rain shadow during the southwest monsoon.
- practice — not a real PYQ
The place in India that records the highest average annual rainfall is
- (a)Jaisalmer
- (b)Mawsynram
- (c)Leh
- (d)Nagpur
Answer(b) Mawsynram — on the crest of the Khasi Hills in Meghalaya, and the wettest place in the world by average annual rainfall.