La-NINA

La-NINA

TOPIC: Geography

Context- The Australian Bureau of Meteorology (BoM) has cited climate models and observations to suggest that the 2021–22 La Nina phenomenon in the Equatorial East and Central Pacific, that drove a successful monsoon for India last year (2021).

Concept-

• El Nino and La Nina are complex weather patterns resulting from variations in ocean temperatures in the Equatorial Pacific Region.
• They are opposite phases of the El Nino-Southern Oscillation (ENSO) cycle.
  • The ENSO cycle describes the fluctuations in temperature between the ocean and atmosphere in the east-central Equatorial Pacific.
• El Nino is a climate pattern that describes the unusual warming of surface waters in the eastern tropical Pacific Ocean.
  • It is the “warm phase” of a larger phenomenon called the El Nino-Southern Oscillation (ENSO). It occurs more frequently than La Nina.
• La Nina, the “cool phase” of ENSO, is a pattern that describes the unusual cooling of the tropical eastern Pacific. La Nina events may last between one and three years, unlike El Nino, which usually lasts no more than a year.
  • La Nina is characterized by lower-than-normal air pressure over the western Pacific. These low-pressure zones contribute to increased rainfall.
  • In the ‘La Nina year’, rainfall associated with the summer monsoon in Southeast Asia tends to be greater than normal, especially in northwest India and Bangladesh.
  • It usually brings in colder than normal winters in India.