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

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 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

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 Class #18 Friday, October 8, 2010

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 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

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 Class #18 Friday, October 8, 2010

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 Class #18 Friday, October 8, 2010

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 Class #18 Friday, October 8, 2010

Fig. 8-39, p. 247