These deviations from the normal surface temperatures in Pacific Ocean 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.
Literally translated as ‘the boy’ and ‘the girl’ in the Spanish language, El Nino and La Nina are the exact opposite phases of a climatic phenomenon called the El Niño-Southern Oscillation (ENSO) cycle, which takes place in the Pacific Ocean. It involves temperature changes in the waters of the Eastern and Central Pacific Ocean. It got the Spanish name after the phenomenon was first identified by Latin American fishermen in the early 17th century.
It is a recurring phenomenon and the change in temperature is accompanied by changes in the patterns of upper and lower level winds, sea level pressure, and tropical rainfall across the Pacific Basin.
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.
Source: Indian Express, 7/09/20
