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El Nino and La Nina
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 by these temperature fluctuations in the Pacific.
El Nino
Derived from the Spanish term which represents “little boy”
It is warmer than normal sea-surface temperatures. It is a warming of the Pacific Ocean between South America and the International Date Line, centered directly on the Equator, and moves towards several degrees of latitude to either side of the equator.
It is laden with high air surface pressure in the western Pacific.
It originated when tropical Pacific Ocean trade winds die out and ocean temperatures become unusually warm.
It has a great impact on season patterns because it makes warmer and drier than average in the Northwest of the pacific during winters and wetter in the Southwest of the pacific and experiences reduced snowfalls.
It decreases the strength of the Coriolis force.
Warm water approaches the coasts of South America which results in reduced upwelling of nutrient-rich deep water impacting impacts on the fish populations.
Wind speed is low.
Heavy rains in Ecuador and Peru;
Heavy rains in southern Brazil but drought in north East Brazil;
Drought in Zimbabwe, Mozambique, South Africa, Ethiopia;
Warm winter in the northern half of the United States and southern Canada.
Drought, Scant rains off Asia including India, Indonesia, and the Philippines; Coral bleaching worldwide; Drought in eastern Australia
La Nina
Derived its name from the Spanish term which represents ‘little girl’.
It is cooler than normal sea-surface temperatures. It originated when cooler than usual ocean temperatures
It contains low air surface pressure in the eastern Pacific
It occurs when the trade winds blow unusually hard and the sea temperature become colder than normal
Winters are wetter and cause above-average precipitation across the Northwest of pacific and drier and below-average precipitation in Southwest of pacific
It increases the strength of the Coriolis force
Coldwater causes increased upwelling of deep cold ocean waters numbers of drought occurrence, with more nutrient-filled eastern Pacific waters.
It had a greater tendency to trigger intense tropical cyclones as wind direction changes pilling up water between Indonesia and nearby areas as winds from Africa onwards get blocked.
Causes drought in Ecuador and Peru. Created low temperature, high Pressure in Eastern Pacific. Heavy floods in Australia; High Temperature in Western Pacific, Indian Ocean, Off coast Somalia and good rains in India.
Impact of El Nino and La Nina on Indian Weather
1. El Nino during winter causes warm conditions over the Indian subcontinent and during summer, it leads to dry conditions and deficient monsoon. Whereas La Nina results in better than normal monsoon in India.
2. India experienced deficient rainfall during El Nino years 2002 and 2009 whereas monsoon was normal during El Nino years 1994 and 1997. It means that in about 50 percent of the year with El Nino during summer, India experienced droughts during monsoon.
3. Crops like Paddy, Maize, Groundnut, Guar, Castor, Tur, Moong, and Bajra would suffer due to El Nino.
Waves and Tides
Waves
Waves are formed when winds blow over the ocean surface. The stronger the wind blows, the bigger the wave becomes.
Wave is formed by various factors such as wind speed, the distance to which the wind slides, width of the area affected by fetch, the length of time the wind has blown over the area, and of course the depth of water.
Tides
Tides are periodic rise and fall of large masses of water. They are caused by the gravitational interaction that exists between the Earth and the Moon.
Tides only occur in the oceans, while waves can be seen in any water body. However, large lakes can sometimes experience small tides.
Tides and waves differ from each other in their method of formation Tides are formed depending on the behavior of the moon and the sun.
