Hazards 5 Tropical Storms

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  • Coriolis force: the rotation of the Earth which deflects objects and air (usually to the right of the northern hemisphere) moving along the Earth’s surface
  • Latent heat: the heat required to turn a solid to a liquid or from a liquid to a gas without a chane in temperature

Nature, Distribution and Magnitude:

  • Usually measure between 200km-700km in diameter
  • The conditions:
    • Sea temperatures above 27℃: source of heat and maintaining rising air currents
    • Ocean depth of 70m: provides latent heat, the rising air causes the moisture to be released by condensation
    • Location at least 5° north or south of the equator: the Coriolis force can bring maximum rotation (Coriolis is weak t the equator)
    • Low level convergence of air in the lower atmospheric circulation system: winds have to come together near the centre of the low pressure zones
    • Rapid outflow of air in the upper atmospheric circulation: pushing away warmer air which has risen to the centre of the storm
  • Distribution
    • Occur between 5° and 20° north and south of the equator, then move westward and are most destructive:
      • Caribbean/Gulf of Mexico
      • Western side of Central America
      • Arabian Sea/Bay of Bengal
      • South East Asia
      • Off Madagascar
      • North-west and north-east Australia
  • Magnitude:
    • Measured using the Saffir-Simpson Scale
    • Measured on a five point scale, with Category 5 characteristics being:
      • Central pressure: 920mb or below
      • Wind speed: 250km/hr or greater
      • Storm surge: 5.5m or greater
      • Damage potential: 

Impacts of Tropical Revolving Storms:

  • Vulnerability depends on:
    • Human factors:
      • The preparations made by the community
      • Warnings and community response
    • Physical factors;
      • Intensity of the storm
      • The length of time over an area
      • Distance from the sea
      • Physical geography of an area (width of costal plain or size of delta)
  • Winds:
    • High winds cause structural damage to the buildings, roads and bridges etc. the debris being flung can also cause threat to people lives
  • Heavy rainfall:
    • Heavy rainfall can cause severe flooding, landslides and mudslides
  • Storm Surges:
    • High sea levels from the wind-driven waves also the ocean heaves up because of the low atmospheric pressure
    • They cause most of the deaths and agricultural areas can suffer for long periods of time as the soil is contaminated with salt water 

Managing Tropical Revolving Storms

  • Prediction:
    • Monitoring and warning systems 
    • National Hurricane Centre in Florida: can access information from geostationary satellite from  land and sea recording centres 
    • Computer models can generate an estimated path and evacuations of areas can be carried out
    • There is a high economic cost associated with evacuation, and false alarms may make people complacent in the future
    • In 1997, a tropical cyclone warning in the Cox Bazar area of Bangladesh allowed for the evacuation of 300,000 people. As a result the death toll was below 100
  • prevention:
    • They cannot really be prevented, but there has been research into the effect of cloud seeding in order to cause more precipitation. The idea is that if the cloud releases more water

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