The atmospheric condition plays vital role in determining the climate of any region.
The climate of India is governed by the following atmospheric conditions
(i) Pressure and Surface Winds
The surface winds blow from region of high pressure to the region of low pressure.
During winter, the high-pressure area lies North of Himalaya. Over the ocean in the South, there is low pressure .So, wind blows from land towards the sea. The reverse occurs during summer.
(ii) Upper Air Circulation
The North Easterly wind originate in sub - tropical high pressure belt of Northern hemisphere. They blow South and get deflected towards right (due to Coriolis force) over the low-pressure area of Indian sub-continent. They are dry and cold, and cause no rainfall.
Sub-tropical westerly jet stream brings Western cyclonic disturbances in North and North - Western India during winter.
(iii) Tropical Cyclone
They are part of easterly flow. They cause heavy to very heavy rainfall in Eastern coast of India during monsoon as well as in October- November.