1. Tropical Cyclones Also: Hurricanes, Typhoons

2. Tropical Cyclone Ingredients Light winds  instability along I.T.C.Z. High humidity (oceans)  fuel (latent heat) Warm surface waters over a vast area (at least 26ºC / 76ºF  tropics, < 25 ºN or S) Will not form within 5 o of equator (no Coriolis )

3. Tropical Cyclone Features Spiral bands No Fronts Eye wall cloud Eye Size: 100-600 miles, but can be larger Death Toll: 12,000

6. Tropical Cyclone Formation Easterly waves (fig. 8-24) –vertical perturbations within the trade winds –about 10% intensify and rotate Tropical depression (winds < 63 kmph, 39 mph) Tropical storm (63-118 kmph, 39-73 mph) –naming of the storm Cyclone (winds > 119 kmph, 74 mph) –Saffir-Simpson scale (Table 8-1) –ranks 1 to 5 (5 is “catastrophic”)

7. Saffir-Simpson Scale

9. Hurricanes, Typhoons & Cyclones World Map shows locations of Hurricanes, Typhoons & Cyclones Names Reflect Locations All are the Same type Of storm

10. Paths of Hurricanes: North Atlantic North Atlantic hurricanes develop 5 to 10 degrees north of The equator & travel to the west, yet as they move farther North they change directions & move eastward Most do not make landfall

11. Tropical Cyclone Timing (Northern Hemisphere)

12. Hurricanes: Coastal Damage/Death Coastal damage can be extensive as high winds, high Tides And ‘storm surges’ push ocean water far inland Galveston, Texas Was struck in 1900 & 6,000 were killed In 1970 a Hurricane Hit Bangladesh & Killed 300,000 in 1991 200,000 died (Note that many people in Australia, Mexico, and S.E. Asia depend on the hurricanes for live-giving moisture each year.)

13. Tropical Cyclone Hazards Storm surge (up to 20 feet) –pressure (1 cm rise per 1 mb drop in pressure) –winds / friction rain / flooding causes most damage! winds tornadoes

14. Tropical Cyclone Power Power –one hour = total USA electricity for one year –one day = nuclear arsenals of USA and Russia Highest U.S.death toll: Galveston, TX, 1900 - 20 ft. storm surge killed 6,000 (1/6 the population)

15. 2005 Atlantic Hurricane Season Most named tropical storms in history (28); including most intense ever (Wilma: 882 millibars; 185 mph sustained winds) and most Category 5 storms (4) everWilma New Orleans destroyed; worst U.S. hurricane damage ever. Cost estimated at: $100,000,000,000 Death toll: at least 2048 confirmed dead as of 4/2006; most were among poorest elderly people.

18. Forecasting and Safety Tracking –satellites –coastal radar Prediction –computer modeling City evacuation plans

19. Midlatitude cyclone Forms outside the tropics. Largest diameter of all storms No eye Has distinct fronts. Extratropical v. tropical cyclones Tropical cyclone Forms over a tropical ocean. Eye and dramatic pressure drop (900 mb or lower) Has no fronts. Smaller average size, but much higher winds.

20. Hurricane & Storm Tracking for the Atlantic & Pacific OceansHurricane & Storm Tracking for the Atlantic & Pacific Oceans - Shows all current hurricanes and their tracks US National Hurricane Center - North Atlantic, Eastern Pacific The Hurricane Hut - Information on all past storms to 1950, along with images and individual storm summaries. Create-a-Cane Interactive fun site from NOAA, allows to specify conditions and see how they impact storm formation NASA Hurricane Web Page - Data, research, science & multimedia resources from NASA WMO guide on cyclone terminology NOVA scienceNOW: Hurricanes US National Hurricane Center The Hurricane Hut Create-a-Cane NASA Hurricane Web Page WMO guide on cyclone terminology NOVA scienceNOW: Hurricanes Hurricane Links