why does the rainfall decrease from east to west in northern india
The rainfall decreases from east to west in northern India because of the following reason:
The inflow of the south-west monsoon into India is such that the windward side of the Western Ghats receives very heavy rainfall, more than 250 cm. The rain shadow region receives scanty rainfall and the moisture laden clouds shed the maximum rainfall of this season in the north-eastern part of the country. Thus, Mawsynram in the southern ranges of the Khasi Dear Studentlls receives the highest average rainfall in the world. Rainfall in the Ganga valley decreases from the east to the west. Hence, Rajasthan and parts of Gujarat which are on the western get scanty rainfall.
Monsoon wind is divided into two branches which brings moister and cause rain-fall across the Indian sub-continent. First south-west branch exhausted its most of the moisture(coming from Arabian Sea) raining over western ghat. When its one branch reaches to western part of north India, it is left with little moisture.
Second branch of monsoon from south-east brings moister from the bay of Bangal and its one branch causes rain in north-east and other moves towards west. The westward flowing monsoon wind causes rain in northern plan. As it moves towards north-west it gets deficient of the moisture, so rainfall decreases from east to west in north India.
The rainfall decreases from east to west as the moisture of the winds decreases. The monsoon winds of the Bay Of Bengal branch exhaust most of the moisture they carry with them.As they get overloaded of the dust particles and water vapour their moisture content gradually decrease and hence their is a gradual decrease in the moisture of the winds.