Download - Class #18: Friday, October 8
Class #18 Friday, October 8, 2010
Class #18: Friday, October 8
Chapter 8 Tropical Cyclones
1
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 2
Fig. 8-29, p. 235
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
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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
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Fig. 8-30, p. 236
Fig. 8-31, p. 237
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
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Fig. 8-32, p. 239
Table 8-3, p. 240
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
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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
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Fig. 8-33, p. 241
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
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Fig. 8-34, p. 242
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
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Box 8-3, p. 243
Box 8-3, p. 243
Flooding in Hurricane Hugo
Fig. 8-35, p. 244
Fig. 8-36, p. 245
Fig. 8-37, p. 245
Fig. 8-38, p. 246
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
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Fig. 8-39, p. 247