2.4.3

Causes of Tropical Storms

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Formation of Tropical Storms

Tropical storms form over water that is 26.5oC or warmer and when there's a small difference in wind speeds between the upper atmosphere and the lower atmosphere.

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Form over warm water

  • Tropical storms form over water that is 26.5oC or warmer.
    • These temperatures are favourable because they mean there's lots of warm, moist air to cause extreme rain. Energy from warm water intensifies cyclones.
  • Lots and lots of energy is released when air evaporates, rises or cools. This increases the speed and energy of a storm.
  • The strength of a storm falls as they move further away from warm water (so when storms are above land or above cooler parts of the ocean). This is called dissipation.
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Move west

  • Near the equator, surface winds are mainly trade winds moving east.
  • The trade winds and something called the Coriolis Effect mean that tropical storms move from east to west.
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Spin

  • The rotation of the Earth causes the Coriolis effect, which makes tropical storms spin by deflecting winds.
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Source areas

  • The source area for most cyclones is between 5o and 30o north and south because the water is below 26.5oC further from the equator.
  • Most cyclones form when sea temperatures are warmest, which is June-November in the northern hemisphere, and November-April in the southern hemisphere.

Jump to other topics

1Paper 1 - Changing River Environnments

2Paper 1 - Changing Coastal Environments

3Paper 1 - Changing Ecosystems

4Paper 1 - Tectonic Hazards

5Paper 1 - Climate Change

6Paper 2 - Changing Populations

7Paper 2 - Changing Towns & Cities

8Paper 2 - Development

9Paper 2 - Changing Economies

10Paper 2 - Resource Provision

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