The south-west monsoon winds originate in the Indian Ocean. The high temperature period during summer gives rise to vast low- pressure areas in the north-eastern regions of India.
South-west monsoon [Climate of India]
The
origin and formation of the winds:
The
south-west monsoon winds originate in the Indian Ocean. The high temperature
period during summer gives rise to vast low- pressure areas in the
north-eastern regions of India. During this time cool and high- pressure area
develops in the Indian Ocean. Thus a system of winds is formed over the Indian
Ocean. These winds are termed as south-west monsoon winds. The south-west
monsoon winds begin io blow from the month of June and continue to blow till
September every year. Kerala, because of its proximity to the Indian Ocean is
the first state to get monsoon winds. The moisture laden monsoon winds bring
heavy rainfall to Kerala in the first week of June. They travel across the
greater part of India during June and September bringing along rainy season in
India. The south-west monsoon winds blow in two branches- the Arabian Sea
Branch and the Bay of Bengal Branch.
The
Arabian Sea Branch:
These
winds blow over the Arabian Sea and strike against the Western Ghats. These
moisture-laden winds are forced to ascend over the slopes of the Ghats giving
along plentiful rainfall to the Western Coastal Plains. The farmers of Kerala,
western Karnataka and southern Maharashtra are the beneficiaries of this branch
of the south-west monsoon winds.
A
section of the Arabian Sea branch moves towards the north and crosses over the
Vindhyas and Satpura ranges. These winds strike against the Rajmahal hills and
cause heavy to very heavy rains in the Chotanagpur regions. Another section of
the Arabian Sea branch travels further north and moves towards Rajasthan. The
Aravalli hills that lie parallel to the direction of the winds help it to reach
Himachal Pradesh. The Aravalli do not act as climatic barriers, thus preventing
Rajasthan to get its share of rainfall.
The
Bay of Bengal branch:
The
moisture laden Bay of Bengal branch of the south-west monsoon winds, on its way
to the north, strikes against the Kasi, Garo and Jaintia Hills. The winds take
a sudden rise over the funnel shaped hills and cause very heavy rains to the
place called Cherrapunji. Incidentally, Cherrapunji records highest rainfall in
India. A section of the winds belonging to the Bay of Bengal branch moves
towards the west and gives rains to the Gangetic plains. The winds then move
further westwards and cause rainfall to the places such as Punjab and Haryana.
The
two branches meet at the Siwaliks:
The
Arabian Sea branch and the Bay of Bengal branch of the monsoon winds meet at
the foot-hills of the Siwaliks ranges of the Himalayan Mountains. The merged
winds give abundant rains along the foothills of the Himalayas. Thus south-west
monsoon winds bring rainfall to the greater part of India. During the entire
rainy season, southern Andhra Pradesh and Tamil Nadu remain dry. This is mainly
because the regions lie on the rain-shadow regions of the south-west monsoon
winds.
Geography of India : Tag: Geography of India : Climate of India - South-west monsoon