What are the Causes of Tropical Storms?

Revision cards on the causes of tropical storms. Information required for your AQA Geography B Unit 2 exam.

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When and Where?

  • when the sea surface temp. is over 27 degrees celcius
  • between 10 degrees and 30 degrees north and south of equator
  • often situated between Tropic of Cancer and Tropic of Capricorn
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Measuring Tropical Storms

Category       Wind speed (km/h)        Effects

1                    120 - 149                      damge to some crops, trees, caravans.

2                    150 - 179                      minor house damage, heavy crop damage.

3                    180 - 209                      some structural damage, power failure likely.

4                    210 - 249                      significant structural damage, widespread power failure.

5                    250 +                            widespread destruction.

(this is called the Saffir-Simpson scale) 

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Stages of Formation

  • Several thunderstorms drift over sea
  • Warm air from sea surface and thunderstorms combine
  • Warm air rises
  • As war air rises and earth turns, air begins to spiral
  • Cools and condenses, forming clouds
  • Air rises faster, cooler air is sucked down
  • Wind speed increases
  • Moves over ocean, picking up warm air
  • Wind speeds reach more than 120 km/h as cold air is draw into eye of storm.
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