INDIAN MONSOON
Monsoon is studied at the global rather than at regional level. Systematic studies of the causes of rainfall in the South Asian region help to understand the causes and salient features of the monsoon, particularly some of its important aspects, such as:
(i) The onset of the monsoon.
(ii) Rain-bearing systems (e.g. tropical cyclones) and the relationship between their frequency and distribution of monsoon rainfall.
(iii) Break in the monsoon.
What is Inter Tropical Convergence Zone (ITCZ)
To understand the Monsoon in India we need to understand the Inter Tropical Convergence Zone (ITCZ)
The Inter Tropical Convergence Zone (ITCZ) is a zone located at the equator and this is a low pressure zone
ITCZ is not a static zone as the earth rotates around the sun in an elliptical order. ITCZ gets shifted.
At ITCZ trade winds converge, and thus, air tends to ascend.
When it is summer in India(from July), the ITCZ is located around 20°N-25°N latitudes (over the Gangetic plain) and when it is winters in India, the ITCZ has been shifted to southward.
Shifting of the ITCZ affects the movement and direction of winds and thus the climate of the earth by shifting the low pressure area from North to South.