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What is La Niña?

Topics Covered: Important Geophysical phenomena such as earthquakes, Tsunami, Volcanic activity, cyclone etc.

What is La Niña?


Context:

The La Niña weather phenomenon is back in the central and eastern equatorial Pacific Ocean after nearly a decade’s absence, the World Meteorological Organization (WMO) said in its latest Global Seasonal update released October 29, 2020.

Implications:

  • La Niña will result in sea surface temperatures between two and three degrees Celsius cooler than average.
  • La Niña could last into 2021, affecting temperatures, precipitation and storm patterns in many parts of the world.

What is La Niña?

It means the large-scale cooling of ocean surface temperatures in the central and eastern equatorial Pacific Ocean, together with changes in the tropical atmospheric circulation, namely winds, pressure and rainfall.

  • It has the opposite impacts on weather and climate as El Niño, which is the warm phase of the El Niño Southern Oscillation (ENSO).

Weather changes because of La Nina:

  1. The Horn of Africa and central Asia will see below average rainfall due to La Niña.
  2. East Africa is forecast to see drier-than-usual conditions, which together with the existing impacts of the desert locust invasion, may add to regional food insecurity.
  3. It could also lead to increased rainfall in southern Africa.
  4. It could also affect the South West Indian Ocean Tropical Cyclone season, reducing the intensity.
  5. Southeast Asia, some Pacific Islands and the northern region of South America are expected to receive above-average rainfall.
  6. In India, La Niña means the country will receive more rainfall than normal, leading to floods.

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InstaLinks:

Prelims Link:

  1. What is El Nino?
  2. What is La Nina?
  3. What is ENSO?
  4. When do these events occur?
  5. Impact of ENSO on Asia, Africa and Australia.

Mains Link:

Discuss the impact of La Nina weather phenomenon on India.

Sources: Down to Earth.