Question

The South West monsoon winds are known for their vagaries____.
a)True
b)False

Answer 1

Hint: Monsoon can be simply defined as periodic reversal of winds which cause rainfall. India receives rainfall under southwest monsoons as well as northeast monsoons.

Complete answer: In the summer, the area near Tibetan plateau gets heated. A low pressure zone is created over north India that attracts moist winds from the high pressure area in the south of Indian Ocean. These winds cause rainfall in most parts of India and are known as southwest monsoons. The shift of subtropical westerly jet towards Tibetan plateau causes the rains.
However monsoon do not come on time every year and differ in intensity from year to year too.A timely northward shift of the subtropical westerly jet at the beginning of summer brings monsoon on time and if this gets delayed then monsoons get delayed too. Similarly intensity is influenced by easterlies as a strong easterly tropical jet results in a strong southwest monsoon over central India, and a weak jet results in a weak monsoon.
Monsoons are weaker in El Niño years, while La Niña years bring particularly strong monsoons. La nina is when eastern pacific waters are colder than normal temperature and hence creating higher pressure than normal years. El Nino on the other hand is years when Pacific waters are warmer than usual.
Also , southwest monsoons are not evenly distributed as some areas like the windward sides of Western Ghat receive heavy rainfall and at the same time central Maharashtra might be going through drought.

Therefore the answer is (A) True.

Note: South west monsoons occur between the months of June to September. Southwest monsoons have two branches-Arabian sea branch and Bay of Bengal branch. Northeast monsoon or winter monsoons occur in the months of December to February and have only one branch. Areas of Tamil Nadu receive rainfall under this monsoon.