Indian Agricultural: Growth, Generation, Policy & Problem Indian Agricultural | Page 53

Pg.no. 52
intertropical convergence zone (ITCZ), a low-pressure belt of highly unstable weather, northward
towards India. This system intensified to its present strength as a result of the Tibetan Plateau's uplift,
which accompanied the Eocene–Oligocene transition event, a major episode of global cooling and
aridification which occurred 34–49 Ma.
The southwest monsoon arrives in two branches: The Bay of Bengal branch and the Arabian Sea
branch. The latter extends towards a low-pressure area over the Thar Desert and is roughly three
times stronger than the Bay of Bengal branch. The monsoon typically breaks over Indian territory by
around 25 May, when it lashes the Andaman and Nicobar Islands in the Bay of Bengal. It strikes the
Indian mainland around 1 June near the Malabar Coast of Kerala. By 9 June, it reaches Mumbai; it
appears over Delhi by 29 June. The Bay of Bengal branch, which initially tracks the Coromandel
Coast northeast from Cape Comorin to Orissa, swerves to the northwest towards the Indo-Gangetic
Plain. The Arabian Sea branch moves northeast towards the Himalayas. By the first week of July, the
entire country experiences monsoon rain; on average, South India receives more rainfall than North
India. However, Northeast India receives the most precipitation. Monsoon clouds begin retreating
from North India by the end of August; it withdraws from Mumbai by 5 October. As India further cools
during September, the southwest monsoon weakens. By the end of November, it has left the country.
Monsoon rains impact the health of the Indian economy; as Indian agriculture employs 600 million
people and comprises 20% of the national GDP, good monsoons correlate with a booming economy.
Weak or failed monsoons (droughts) result in widespread agricultural losses and substantially hinder
overall economic growth. Yet such rains reduce temperatures and can replenish groundwater tables,
rivers.
Post-monsoon
During the post-monsoon months of October to December, a different monsoon cycle, the northeast
(or "retreating") monsoon, brings dry, cool, and dense air masses to large parts of India. It is called
autumn. Winds spill across the Himalayas and flow to the southwest across the country, resulting in
clear, sunny skies. Though the India Meteorological Department (IMD) and other sources refers to
this period as a fourth ("post-monsoon") season, other sources designate only three seasons.
Depending on location, this period lasts from October to November, after the southwest monsoon has
peaked. Less and less precipitation falls, and vegetation begins to dry out. In most parts of India, this
period marks the transition from wet to dry seasonal conditions. Average daily maximum
temperatures range between 28 and 34 °C (82 and 93 °F).
The northeast monsoon, which begins in September, lasts through the post-monsoon seasons, and
only ends in March. It carries winds that have already lost their moisture out to the ocean (opposite
from the summer monsoon). They cross India diagonally from northeast to southwest. However, the
large indentation made by the Bay of Bengal into India's eastern coast means that the flows are
humidified before reaching Cape Comorin and rest of Tamil Nadu, meaning that the state, and also
some parts of Kerala, experience significant precipitation in the post-monsoon and winter periods.
Ramesh Kumar P