UPPCS Mains- 2018 answer writing practice
Discuss the phenomenon of El nino and La nina. How they impact the world weather pattern? (200 words)
एल नीनो और ला नीना की घटना पर चर्चा करें। वे विश्व मौसम पैटर्न को कैसे प्रभावित करते हैं? (200 शब्द)
El Niño and La Niña are opposite phases of the El Niño-Southern Oscillation cycle (ENSO). The ENSO cycle describes fluctuations in temperature of the ocean surface and the fluctuations in the atmospheric pressure in the East-Central Equatorial Pacific.
El Niño: A warm ocean current develops along Peruvian coast replacing cold Peruvian current, leading to increase in sea surface temperatures and weakening of trade wind, which weakens the Walker circulation and El Niño results. This normally occurs every 3-5 years, close to Christmas across central and EastCentral Equatorial Pacific region.
Global weather impacts of El Niño:
• Increased Rainfall: Heavier rainfall occurs during El Niño years in China, Peru, Chile, Equador, Northern Argentina, Equatorial East Africa, Southern USA, etc.
• Reduced rainfall: Due to El Niño, there is reduced rainfall and drier conditions in the Indian subcontinent (Generally, Indian monsoons and El Niño are inversely related), Indonesia, Australia, Southern Africa, Saudi Arabia, etc.
• El Niño events produce more tropical storms and hurricanes in the Eastern Pacific.
La Niña: La Niña is associated with cooler-than-average sea surface temperatures in the central and
eastern tropical Pacific Ocean due to strong, eastward-moving trade winds and ocean currents that bring
the cold water to the surface through upwelling. During La Niña, the Walker Circulation is enhanced and
becomes very pronounced with well-defined rising and sinking branches.
Global weather impacts of La Niña:
• Increased rainfall: La Niña leads to increased rainfall in the Indian subcontinent, particularly India
and Bangladesh, Southern Africa region, Indonesia, Australia, Saudi Arabia, Pacific North-West and
Western Canada, among others.
• Decrease in rainfall: Due to La Niña, there is reduced rainfall inEquatorial East Africa, China, Southern
USA, Argentina, Peru, Chile, etc.
• La Niña cycles produce more Atlantic and Caribbean Sea hurricanes.
In this way, it atmospheric circulations show that changes at one place affects the weather in other parts
of the world.
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