Cyclones, Hurricanes and Tsunamis EVS Grade 5 | Orchids
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Natural Disasters

Concept: Cyclones, Hurricanes and Tsunamis

Both cyclones and hurricanes are types of tropical storms. So before getting to know cyclones, hurricanes and tsunamis, let us learn about tropical storms.

What are tropical storms?

  • Tropical storms are highly destructive circular storms that bring strong winds with heavy rains.
  • These storms can uproot trees and destroy concrete buildings.
  • Tropical storms have different names in different places.
  • These storms occur across the equatorial region.
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How tropical storms are formed?

  • Tropical storms are formed over the warm areas of oceans.
  • These are mostly formed over the Pacific, Atlantic and Indian oceans.
  • Across the equatorial region, where warm weather prevails, due to evaporation, the air over the ocean surface rises upward.
  • As a result, an area of low air pressure is created right above the ocean surface.
  • The cool air from the surrounding areas of high pressure rushes to the area of low pressure, gets heated and rises up by the process mentioned above.
  • The evaporated hot air cools and condenses to form clouds.
  • As this above-mentioned process gets constantly repeated, it leads to the formation of a huge system of clouds and swirling winds.
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  • This system of clouds and winds gets stronger due to the continuous evaporation of ocean water and swirls at a very high speed around a centre known as the eye of the storm.
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  • These strong rotating winds approach the land, hit the landmass and cause widespread destruction. This phenomenon is called landfall of the storm.
  • When the wind speed of a tropical storm exceeds 119 kilometres per hour, it transforms into a cyclone.

Different names of tropical storms:

  • Cyclones: These tropical storms are formed above the Indian Ocean.
  • Hurricanes: These tropical storms are formed above the North Atlantic Ocean.
  • Typhoons: These tropical storms are formed above the Pacific Ocean.
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Characteristics of cyclones and hurricanes:

  • A cyclone looks like a rotating disk of a cloud surrounding a centre from above.
  • These storms hit the landmass with heavy rainfall and strong, gusty winds.
  • A cyclone storm gradually loses its energy while it moves towards the interior of the land.
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Effects of cyclones and hurricanes:

  • Cyclones and hurricanes are devastating storms accompanied by strong winds that uproot trees and destroy houses and buildings.
  • Excessive rain during or after a cyclonic storm or hurricane may cause floods that cause waterlogging.
  • Flood and waterlogging contaminate water and spread many waterborne diseases like typhoid, jaundice, cholera, dysentery, etc.
  • Cyclonic storms can produce huge waves in the sea, which is fatal for fishers and trawlers.
  • These storms cause severe casualties in the cities as well.
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Preventive measures against cyclones and hurricanes:

  • During cyclones, we should turn off all electric appliances.
  • We should store enough drinking water and dry food at home.
  • We should not go out and close all doors and windows until the storm stops.
  • We should keep our emergency kit and first aid kit ready.
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Tsunami:

‘Tsunami’ is a Japanese word which means deadly, giant ocean waves. The characteristic feature of a tsunami is that a series of massive ocean waves gradually increase in height when reaching the shoreline.

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Causes of tsunami:

  • A tsunami is an aftereffect of a sudden underwater earthquake or volcanic eruption.
  • When earthquakes happen underwater, the tectonic plates of the ocean floor either rise or move down, which causes a sudden displacement of the ocean water, creating massive waves.
  • Underwater landslides can produce giant waves in the ocean.
  • When lava enters the ocean due to a sudden volcanic eruption underwater, it may generate gigantic waves in the sea.
  • Tsunami waves are formed when huge meteorites fall into the ocean.
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Effects of tsunami:

  • A tsunami is a devastating natural disaster that injures humans and livestock, uproots trees, and destroys houses, buildings and other man-made structures.
  • A tsunami can cause floods and waterlogging on nearby beaches and contaminate drinking water.
  • The giant waves of a tsunami can cause fatal accidents like explosions and outbreaks of fire.
  • A tsunami can destroy electric poles and affect the electricity supply in various places.
  • It can also disrupt the modes of communication in a region.
  • Lastly, a tsunami also affects the economy of a country.
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New Words:

Swirl: A continuous movement in a twisting or rotating pattern surrounding a centre.

Dysentery: Diarrhoea accompanied by blood is called dysentery.

Trawlers: A fishing boat that is used in the deep sea for fishing using a large fishing net.


Did You Know?

  • The system of winds in a cyclonic storm moves anti-clockwise in the Northern Hemisphere and clockwise in the Southern Hemisphere.
  • The Great Bhola Cyclone is one of the most devastating cyclones to date that struck India’s West Bengal and Bangladesh in the year 1970.
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