class #10: tuesday, july 20 hurricanes

Class #10, Tuesday. July 20, 2010 1

Class #10: Tuesday, July 20Hurricanes

Chapter 15


hurricanes

Chapter 15

Class #10, Tuesday. July 20, 2010 3Fig. 15-CO, p. 410


Tropical Weather

• Noon sun is always high, seasonal temperature changes small

• Daily heating and humidity = cumulus clouds and afternoon thunderstorms

• Non-squall clusters, tropical squall line, tropical wave

• Seasons defined by precipitation as opposed to temperature


Anatomy of a Hurricane

• Intense storm of tropical origin with winds greater than 64kts; typhoon, cyclone, tropical cyclone

• Eye• Eye wall• Spiral rain band• Anticyclonic divergence• Latent heat

Class #10, Tuesday. July 20, 2010 7Fig. 15-2, p. 413

Class #10, Tuesday. July 20, 2010 9Stepped Art

Fig. 15-3, p. 414


Fig. 15-3, p. 414


Hurricane Formation and Dissipation

The Right EnvironmentTropical waters with light wind26.5°C sea surface temperatures (June-November)Surface converge trigger (tropical wave)Coriolis effect: 5-20º latitude

The Developing StormCluster of thunderstorms around a rotating Low

pressureRelease of latent heat, divergence aloft

Class #10, Tuesday. July 20, 2010 19Fig. 1, p. 419



• The Storm Dies Out– Cold water, land

• Hurricane Stages of Development– Tropical Disturbance– Tropical Depression (22-34kts)– Tropical Storm (35-64kts)– Hurricane (> 65kts)



Topic: Hurricanes and Mid-latitude StormsHurricane warm core lowMid-latitude cold-core lowArctic hurricanesHurricane + upper level trough = mid-latitude

cyclone Hurricane movement

General track: west, northwest, northeastMuch variation


Fig. 15-12, p. 421


Naming Hurricane and Tropical Storms

• Process has changed over the years:– Latitude and longitude– Letters of the alphabet– Alphabetical female names– Alphabetical, alternating female and male names– Retirement (Katrina, Camille)


Devastating Wind, Storm Surge, and Flooding

• Highest winds on the eastern side of storm (wind + speed of storm)

• Swell• Storm surge on north side of storm (tide)• Coastal flooding• River flooding• Hurricane spawned tornadoes• Saffir-Simpson scale – 1 weakest, 5 strongest

Class #10, Tuesday. July 20, 2010 31Table 15-1a, p. 423

Class #10, Tuesday. July 20, 2010 32Table 15-1b, p. 423


Some Notable Storms

• Camille 1969• Hugo 1989• Andrew 1992• Ivan 2004• Katrina 2005


Some Notable Storms

Observation: Atlantic Hurricanes 2004-2005Abnormally warm ocean water and weak vertical

sheer allowed for high frequency of hurricanes Environmental Issue: Hurricanes in a Warmer

WorldNo clear answer, need more dataIntensity and frequency most likely to be

impacted.

Class #10, Tuesday. July 20, 2010 41Table 15-2, p. 426

Class #10, Tuesday. July 20, 2010 42Table 15-3, p. 427


Fig. 4, p. 431


Hurricane Watches, Warnings, and Forecasts

• Watch issued 24-48 hours before hurricane expected to make landfall

• Warning issued when storm expected to strike coast within 24 hours and probability of strike in a given location provided.


Fig. 15-27, p. 433


Modifying Hurricanes

• Operation STORMFURY: seed clouds to create rain, weaken hurricane, and reduce winds; no conclusive evidence it was effective

• Oil or film on water to reduce evaporation and latent heat available to storms

class #10: tuesday, july 20 hurricanes

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