Hurricanes & Typhoons


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Hurricanes & Typhoons

  1. 1. Hurricanes & Typhoons By: Momina & Vanessa
  2. 2. What is a Hurricane? <ul><li>A hurricane is a large, spinning wind system that develops over warm seas near the equator </li></ul><ul><li>Hurricanes are technically tropical revolving storms </li></ul><ul><li>They are characterized by rotating winds that have the speed of about 75 mph </li></ul>
  3. 3. ( continued) <ul><li>The tropics mostly have the most extreme weather conditions </li></ul><ul><li>The air heated by the sun rises swiftly which creates areas of very low pressure, the warm air rises then it becomes loaded with moisture </li></ul><ul><li>It creates into a massive thunder cloud </li></ul><ul><li>It can be formed into a huge circle that can be up to 1,200 miles across </li></ul>
  4. 4. A Hurricane Begins <ul><li>Hurricanes usually begin in the steamy, late summer in the tropics, when the seas are the warmest </li></ul><ul><li>For the hurricanes to develop, the sea surface temperature has to be at least 78 degrees Fahrenheit </li></ul><ul><li>When the warm air rises from the seas and condenses into clouds </li></ul><ul><li>The result of this mixture of heat and moisture is often a collection of thunderstorms, from which a tropical storm can develop </li></ul><ul><li>During the hurricane season, the coriolis effect of the earth’s rotation starts the winds in the thunderstorm spinning in a circular motion </li></ul><ul><li>At the center of the storm is a calm, often cloudless area called the eye, where there is no rain, and the winds are fairly light </li></ul>
  5. 5. The Buildup <ul><li>As the hurricane builds up it begins to move </li></ul><ul><li>It is sustained by a steady flow of warm, moist air </li></ul><ul><li>The strongest winds and heaviest rains are found in the towering clouds which merge into a wall about 12-18 miles from the storm’s center </li></ul>
  6. 6. (continued) <ul><li>Winds around the eye can reach speeds of up to 125 mph and a fully developed hurricane pumps out about two million tons of air per second </li></ul><ul><li>The hurricane travels at speeds of between 10 &30 mph </li></ul><ul><li>When it hits an area of cold sea or land, it enters a cold, inhospitable climate, where its supply of moist air is cut off </li></ul>
  7. 7. (continued) <ul><li>The eye quickly disappears and the storm begins to die down </li></ul><ul><li>Yet it is when it hits the land that a hurricane, typhoon, or cyclone causes most damage </li></ul><ul><li>90% of victims are claimed when the storm first smashes ashore, bringing with it not only powerful winds, but huge waves called storm surges </li></ul>
  8. 8. The Storm Surge <ul><li>The deadly companion of every tropical storm is the storm surge; the huge mounds of seawater that are whipped up by the powerful winds </li></ul><ul><li>The first sign is a storm surge can occur nearly a week before the actual hurricane, typhoon, or cyclone </li></ul><ul><li>Winds move outward much faster than the storm itself and whip up the sea into waves up to 5 ft. high along the costline </li></ul>
  9. 9. (continued) <ul><li>When the storm is about 110 mi. from land, huge waves driven by its winds begin to crash ashore </li></ul><ul><li>The deafening roar of the surf can be heard miles inland </li></ul><ul><li>This is followed by the most deadly and destructive element of the surge as the huge bulge of water that forms beneath the storm’s eye smashes ashore </li></ul>
  10. 10. (continued) <ul><li>Low-lying coastal areas can be devastated by the severe floods that result, and many lives and homes are often lost </li></ul>
  11. 11. The Damage <ul><li>For anyone caught in a hurricane, the experience is a terrifying one. </li></ul><ul><li>Fierce, whirling winds rip across the countryside, overturning cars and heavy trucks </li></ul><ul><li>Trees are ripped from the ground, and whole buildings can be lifted from their foundations </li></ul>
  12. 12. (continued) <ul><li>Some of the worst disasters occur near coastal areas, where stormy seas contribute to the havoc that is wreaked </li></ul><ul><li>In 1938, one of the most powerful hurricanes in history swept through Long Island, New York </li></ul><ul><li>In just seven hours, the storm killed at least 600 people and destroyed the homes of over 60,000 </li></ul>
  13. 13. (continued) <ul><li>The total damage was estimated at the enormous sum of one-third of one billion dollars </li></ul><ul><li>The storm destroyed26,000 cars and 29,000 miles of electric, telegraph, and telephone wires and flooded thousands of acres of land </li></ul>
  14. 14. (continued) <ul><li>One coastal area on the island was so badly it hit by the hurricane that 200 homes there were completely swept away </li></ul><ul><li>Rescue workers searching for missing people had to use maps from telephone companies to identify the sites on which the houses once stood </li></ul>
  15. 15. Are We Causing More? <ul><li>Hurricanes are sustained by warm, moist air </li></ul><ul><li>The countries of northern Europe have a fairly cool climate </li></ul><ul><li>So why have they been hit by hurricanes in recent years </li></ul><ul><li>One theory is that global warming is having some effect </li></ul>
  16. 16. (continued) <ul><li>As the planet heats up, more parts of the world are developing the kind of climate that is ideal for tropical storms </li></ul><ul><li>The gases in earth’s atmosphere act like the glass of a greenhouse, trapping enough heat from the sun to keep the planet warm enough for life </li></ul>
  17. 17. (continued) This is known as the “Greenhouse Effect”. One of the main greenhouse gases is carbon dioxide. Other greenhouse gases are methane, water, vapor, and chlorofluocarbons. The only way we can prevent global warming is by controlling the amounts of theses gases that are released into the atmosphere.