What is La Nina – how it impacts India’s monsoon?

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El Nino is typically  known as the warm phase and La Nina is identified as the cold phase of ENSO. These deviations from the normal surface temperatures can potentially have a large-scale impact on the global weather conditions, and the monsoon climate of the Indian subcontinent also gets affected with these temperature fluctuations in the Pacific.

What is La Nina?

Also known as ‘El Viejo’ or cold event, El 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. Generally, El Nino and La Nina occur every 4 -5 years. El Nino is more frequent than La Nina.