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Class #18: Friday, October 8. Chapter 8 Tropical Cyclones. Review sheet for test #2. Test is on Wednesday, October 13 Test covers chapters 6, 7, 8 except for the material in boxes 6.1 (p.162), 6.2 (pp. 168-9), 6.3 (pp. 176-7), 7.1 (p.196), and 7.2 (p.204).
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Class #18: Friday, October 8 Chapter 8 Tropical Cyclones Class #18 Friday, October 8, 2010
Review sheet for test #2 • Test is on Wednesday, October 13 • Test covers chapters 6, 7, 8 except for the material in boxes 6.1 (p.162), 6.2 (pp. 168-9), 6.3 (pp. 176-7), 7.1 (p.196), and 7.2 (p.204). • Format of the test will be similar to test #1 Class #18 Friday, October 8, 2010
More about the life cycle of tropical cyclones • Some go on to become extratropical cyclones in middle latitudes • In the Western Pacific Ocean, an occasional typhoon will go on to become a supertyphoon. These have sustained winds > 150 miles per hour • A widening eye usually indicates a weakening of the storm Class #18 Friday, October 8, 2010
More about the life cycle of a tropical cyclone • On a day to day basis, the intensity of tropical cyclones is influenced by the sea surface temperatures it encounters. • The hurricane season of 2005 broke many records for tropical cyclones—27 named storms in the North Atlantic Class #18 Friday, October 8, 2010
How hurricanes cause destruction • Winds: hurricanes are classified as to wind damage using the Saffir-Simpson scale from 1 (weakest) to 5 (strongest) • Hurricanes can contain “mini-swirls” that are tornado-sized with even stronger winds than the main hurricane Class #18 Friday, October 8, 2010
How hurricanes cause destruction • The storm surge is the process of wind-induced seawater flooding • Causes 90% of hurricane deaths • Worst at high tide (new and full moon) • Worst with strong winds • Worst with lowest sea-level pressure • Worst with low-lying land • Depends on coastal and underwater shape Class #18 Friday, October 8, 2010
How hurricanes cause destruction • Rainwater causes flooding • From 1970-2000 more deaths were caused by flooding than other types of hazards in hurricanes • Massive flooding can occur with even weak tropical cyclones or tropical storms • Hurricane rains have some beneficial effects Class #18 Friday, October 8, 2010
How hurricanes cause destruction • Flooding from tropical storm Allison in June 2001 killed at least 20 people and damaged houses with costs near $5 billion • Allison caused rain in every Gulf and Atlantic state from Texas to Maine • Allison caused nearly 36 inches of rain in Houston, TX Class #18 Friday, October 8, 2010
Forecasting and tracking hurricanes • The story of Bryan Norcross • Broadcast weather information during hurricane Andrew in Florida in 1992 • Andrew was a category 5 hurricane • Norcross remained on the air when many of the other stations were off the air • He broadcast forecasts and valuable information about safety in hurricanes Class #18 Friday, October 8, 2010
Flooding in Hurricane Hugo Fig. 8-35, p. 244
Long-term forecasting of hurricanes • These forecasts are less than perfect • They rely heavily on the cycles of El Niño and La Niño for forecasting in the North Atlantic Class #18 Friday, October 8, 2010