NORTH EAST MONSOON

Subject: Geography

Context: Northeast monsoon is likely to set in after october 25 according to Indian Meteorological Department,

Concept:

• October to December is recognised as the period for Northeast monsoon by the India Meteorological Department (IMD).
• The northeast monsoon (winter monsoon) blows from land to sea.
• During this period, rainfall is experienced over southern states, mainly Tamil Nadu, Kerala, Andhra Pradesh along with some parts of Telangana and Karnataka.
• In areas around Jammu and Kashmir, Himachal Pradesh, Uttarakhand and along the northeast, precipitation during this period reported is either in the form of rainfall or snowfall.
• It can be noted that many other parts of the country, like the Gangetic plains and northern states, also receive rain in November and December but this is not due to the northeast monsoon.
• It is caused mainly by the Western Disturbances, an eastward-moving rain-bearing wind system that originates beyond Afghanistan and Iran, picking up moisture from as far as the Mediterranean Sea, even the Atlantic Ocean. In the higher reaches of Jammu and Kashmir, Himachal Pradesh, and Uttarakhand, the precipitation is often in the form of snow.
• The northeast monsoon does not have anything to do with northeast India. It derives its name from the direction in which it travels, from the northeast to the southwest.

What is La Nina?

• Also known as ‘El Viejo’ or cold event, La Nina is observed when the water temperature in the Eastern Pacific gets comparatively colder than normal, as a consequence of which, there is a strong high pressure over the eastern equatorial Pacific. The difference in pressure between Eastern Pacific and Western Pacific/Asia causes a moisture-laden wind movement from East to West Pacific and Asia.
• As a result, La Nina causes drought in the South American countries of Peru and Ecuador, heavy floods in Australia, high temperatures in Western Pacific, Indian Ocean, off the Somalian coast and a comparatively better monsoon rains in India.(However often considered unfavourable for northeast monsoon over states like TN).Generally, El Nino and La Nina occur every 4 -5 years. El Nino is more frequent than La Nina. 

India Meteorological Department

• It was established in 1875.
• It is an agency of the Ministry of Earth Sciences of the Government of India.
• It is the principal agency responsible for meteorological observations, weather forecasting and seismology.