1.
The Mechanism of the Indian Monsoon

2.
• The monsoons are the seasonal winds that blow from
sea to land for two to five months in the tropical lands.
• It is the complete replacement of the dry hot air by the
equatorial maritime air up to an altitude of three to five
kilometers over the land and water surface.
• Meteorologists have found a sea-saw kind of
relationship between the meteorological changes over
the Pacific and Indian Oceans. Whenever the surface
pressure is high in the sub-tropical region of the Pacific
Ocean in the northern hemisphere, the pressure over the
southern part of the Indian Ocean tends to be low and
vice versa

3.
• Meteorologists have found a sea-saw kind of
relationship between the meteorological changes
over the Pacific and Indian Oceans. Whenever the
surface pressure is high in the sub-tropical region of
the Pacific Ocean in the northern hemisphere, the
pressure over the southern part of the Indian Ocean
tends to be low and vice versa. This causes the
shifting of the winds across the equator in different
seasons.
• This shifting of the winds across the equator is called
the ‘Southern Oscillation’

4.
• In the summer season of Northern Hemisphere the
pressure over the Indian Ocean is low compared to
the pressure over the Pacific Ocean in the Southern
Hemisphere.
• Thus the winds from the Pacific Ocean blow towards
the Indian Ocean.
• In south of the Equator the direction of the wind is
from south east to north west but as it crosses the
Equator it becomes south west to north east.

5.
• This change in direction occurs due to the rotation of
the earth ie; the Coriolis force.
• Ferrel’s had stated that all the winds in the Northern
Hemisphere get deflected to their right and all the
winds in the Southern Hemisphere get deflected to
their left.
• Since the monsoon winds enter India from the south
west direction we call it the South West Monsoon.

6.
WIND DIRECTION DURING THE MONSOON SEASON