Indian Monsoon

Moist monsoon winds from the Arabian Sea are forced to rise when they strike the windward slope of the Western Ghats. As the air rises, it cools, water vapour condenses, and rain falls; this is orographic rainfall. Option B describes convectional rainfall, while air descending on the leeward slope usually becomes warmer and drier. Exam tip: Forced uplift of air over a mountain indicates orographic rainfall.

Moisture falls as rain on the windward slope. Therefore the leeward side receives less rainfall.

The Bengal branch gives rainfall while moving from east to west. Its moisture reduces and rainfall may decrease in the west.

The Bay of Bengal branch carries moisture and strikes hills. This causes heavy rainfall in the north-east.

In Mawsynram moist monsoon winds rise after striking hills. Therefore relief is also a main reason.

The Aravalli does not lift winds sufficiently. Therefore conversion of moisture into rainfall remains limited in western Rajasthan.

Ladakh lies in the rain-shadow of the Himalaya and is far from the sea. Therefore it has low rainfall and cold conditions.

In burst of monsoon rainfall starts sharply at the time of arrival. Link it with the beginning of the south-west monsoon.

If rainfall stops during monsoon, plants may face water shortage. Therefore regular rainfall is also important.

Timing and distribution are decisive along with total rainfall. Rainfall at the wrong time may not benefit crops.

Excess rain in some places causes floods and deficiency elsewhere causes drought. Always understand monsoon distribution regionally.

The monsoon trough affects rainfall zones. Its position can change the area and intensity of rainfall.

Monsoon generally enters from Kerala and then advances over the country. Withdrawal occurs in stages.

North-east winds pick moisture while crossing the Bay of Bengal. This causes rainfall on the Tamil Nadu coast.

For the south-west monsoon, Tamil Nadu can lie on the leeward side. Therefore it receives more rain from the north-east monsoon.

Low pressure systems can develop during retreating monsoon. This increases cyclone risk on the eastern coast.

Monsoon rainfall is the base of water storage, river flow and groundwater recharge. Therefore it is very important in water planning.

Low rainfall increases pressure on reservoirs and groundwater. It can affect urban water supply along with agriculture.

Indian agriculture is deeply linked with monsoon rainfall. Therefore monsoon affects food production and availability.

A large part of rural livelihood depends on farming, livestock rearing and local water resources. Monsoon rainfall affects crop sowing, water for irrigation, fodder availability and water for animals; therefore, monsoon and rural livelihood must be studied together. Option B is incomplete because the impact is not limited to rural market prices. Exam tip: Link monsoon effects with agriculture, water and livestock.