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Topic – Salient features of world’s physical geography.
3) What are the causes and effects of El-Nino. Discuss.(250 words)
Discuss- this is an all-encompassing directive which mandates us to write in detail about the key demand of the question. we also have to discuss about the related and important aspects of the question in order to bring out a complete picture of the issue in hand.
Key demand of the question.
The question wants us to write at length about the causes/ factors which lead to El-Nino and also write in detail about its effects on the world climate and geography.
Structure of the answer
Introduction– write a few introductory lines about the El-Nino. E.g El Niño is a naturally occurring phenomenon that is linked to a periodic warming in sea surface temperatures across the central and east-central Equatorial Pacific. El Niño is Spanish for “the boy child,” which is often used to refer to Jesus Christ, and the phenomenon earned this name because it typically occurs in December around Christmas. El Niño occurs every 2-7 years, and can last anywhere between nine months and two years.
- Discuss the causes of El-Nino. E.g
- The trade winds push warm water on the surface of the ocean from east to west (westerly). This causes the warm water to build up on the western side of the ocean near Asia.Meanwhile, on the eastern side of the ocean, near Central and South America, cold waters are pushed up towards the surface.
- Because of this, there is a difference in temperature across the equatorial pacific, with warm water to the west and cold water to the east.The warm water in the west heats the air, making the warm air rise and leading to drastic weather, including rain and thunderstorms.
- The rising warm air causes a circulation between east and west in the Pacific, with the warm, moist air rising in the west, and cool, dry air descending in the east.All of these natural occurrences lead to a reinforcement of the easterly winds, and cause a self-perpetuating motion in the air in the Pacific.
- Under the proper conditions, the trade winds are weakened, causing less warm surface water to be pushed to the west, and less cold water to be pulled to the surface in the east. Parts of the ocean that are cold during the usual self-perpetuating cycle become warmer, cancelling out the normal difference in temperature in the equatorial Pacific between east and west etc.
- Discuss the effects of El-Nino. E.g
- In South America, there is a drastic increase in the risk of flooding on the western coast, while there is an increase in the risk of droughts on parts of the eastern coast.
- In eastern countries, like India and Indonesia, there is an increase in droughts.
In general, El Niño causes vast amounts of rainfall in the eastern parts of the Pacific (the western coast of South America), and very dry weather on the western parts (India, Indonesia).
- With all the extra heat at the surface of the Pacific Ocean, energy is released into the atmosphere, causing an overall warming of the global climate temporarily. Years in which El Niño occurs tend to feature higher temperatures across the globe.
- The effects of El Niño on the weather peak in December and can last for several months after that etc.
Conclusion- based on your discussion, form a fair and a balanced conclusion on the given issue.