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Lesson 3: Tropical storms


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Lesson 3: Tropical storms

  1. 1. Tropical Storms Mr. T. Tonna
  2. 2. Index • What are Tropical Storms? • How and Where do they form? • Main Features of a Tropical Storm. • Recent Tropical Storms • Case Study: Hurricane Katrina, 2005. • Destructiveness of Tropical Storms • Summary Mr. T. Tonna
  3. 3. What are Tropical Storms? • Tropical storms are areas of intense low pressure. • They produce violent weather with high winds (The average speed is 120 km/h. Although it may vary from 32 km/h to 200 km/h or more. At times it reaches 400 km/h also), thick cloud and torrential rain. • Depending on where they are in the world they can also be called: – Hurricanes – Cyclones – Typhoons Mr. T. Tonna
  4. 4. How and Where do they Form? • There are three main criteria needed for a tropical storm to develop: - Warm Tropical Oceans (Temperature of 26 C or more) - Late Summer early Autumn where sea temperature is optimum. - In Certain Latitudes: 5 -20 North and South. Mr. T. Tonna
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  8. 8. Main Features of Tropical Storms Mr. T. Tonna
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  10. 10. • Warm air and water vapour is ‘sucked’ up from the oceans in the centre of the storm cell. • This air then cools and as it condenses it forms clouds and then releases its huge energy that powers the storm. • Once the storm makes landfall the source of heat (the ocean) is lost and the storm decreases in strength. • Tropical storms tend to move westwards when over seas and polarly once they have hit land. Mr. T. Tonna
  11. 11. • Tropical Storms are at their most powerful either when at sea or at landfall due to the presence of thermal energy. • Due to the high winds present, storm surges are common and these increased depending on the category of the storm. • Tropical Storms are categorised according to the Saffir-Simpson Hurricane Scale based on their wind Speeds and resulting damage. Mr. T. Tonna
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  15. 15. Recent Powerful Tropical Storms • Typhoon Haiyan, Philippines- November 2013 • Hurricane Sandy, North-East USA, October 2012 • Hurricane Katrina, South-East USA, August 2005 • Hurricane Ivan, South-East/East USA, September 2004. Mr. T. Tonna
  16. 16. Case Study: Hurricane Katrina • Hurricane Katrina formed as Tropical Depression over the south-eastern Bahamas on August 23, 2005. • The tropical storm moved towards Florida, and became a hurricane only two hours before it made landfall on August 25. • It weakened over land but soon ended up in the Gulf of Mexico where it regained it’s Strength, going from category 3 to 5 in 9 hours. Mr. T. Tonna
  17. 17. Mr. T. Tonna Below: The Course of Hurricane Katrina, 2005 Left: The Saffir-Simpson Hurricane Wind Scale used to measure the Category of Hurricanes.
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  19. 19. Hurricane Katrina Over New Orleans • New Orleans is the largest city in the state of Louisiana. • It is located 2-6m below sea level which is why Hurricane Katrina was so devastating. • Over New Orleans Katrina had: – Wind Gusts over 175miles per hour (over 280km/h) – Levees protecting the city from flooding collapsed due to the wind and storm surge (7 Feet High) produced by Katrina – An estimated 80 percent of New Orleans was under water, up to 20 feet deep in places. – The centre eye had extremely low pressure: 920 mbar. Mr. T. Tonna
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  22. 22. Destructive Results of Katrina • Despite an evacuation order, many of the poorest people remained in the city. • People sought refuge in the Super Dome stadium. Conditions were unhygienic • shortage of food and water. • Looting was commonplace throughout the city. • The final death toll was at 1,836: Louisiana (1,577) /Mississippi (238) • 1 million people homes destroyed $81 billion in damages. • Oil facilities were damaged and as a result petrol prices rose in the UK and USA. • Total Estimated Damages exceeded $150 billion in Louisiana and Mississippi alone. Mr. T. Tonna
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  25. 25. Summary • Tropical Storms can only be found in the Lower latitudes between 5 -20 North and South where sea temperature exceeds 27 C. • They usually occur between late summer and early Autumn. • Hurricane Katrina was one of the most destructive Tropical storms ever to hit Mainland USA. • It is a pure example of how quickly a ‘contained’ storm can change into a cataclysmic event. • The storm showed just how costly Tropical storms could be, with an estimated damage cost exceeding $150billion. Mr. T. Tonna