Class #10, Tuesday. July 20, 2010 1

Class #10: Tuesday, July 20Hurricanes

Chapter 15

Class #10, Tuesday. July 20, 2010 2

hurricanes

Chapter 15

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

Class #10, Tuesday. July 20, 2010 4

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

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Class #10, Tuesday. July 20, 2010 6

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 8Fig. 15-3, p. 414

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

Fig. 15-3, p. 414

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

Fig. 15-3, p. 414

Class #10, Tuesday. July 20, 2010 11Stepped Art

Fig. 15-3, p. 414

Class #10, Tuesday. July 20, 2010 12Fig. 15-4, p. 415

Class #10, Tuesday. July 20, 2010 13Fig. 15-5, p. 415

Class #10, Tuesday. July 20, 2010 14Fig. 15-6, p. 415

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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

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Class #10, Tuesday. July 20, 2010 17

Class #10, Tuesday. July 20, 2010 18

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

Class #10, Tuesday. July 20, 2010 20

Hurricane Formation and Dissipation

• The Storm Dies Out– Cold water, land

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

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Class #10, Tuesday. July 20, 2010 22

Hurricane Formation and Dissipation

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

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Class #10, Tuesday. July 20, 2010 24

Class #10, Tuesday. July 20, 2010 25Stepped Art

Fig. 15-12, p. 421

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Class #10, Tuesday. July 20, 2010 27Fig. 15-14, p. 422

Class #10, Tuesday. July 20, 2010 28

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)

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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

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

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

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Class #10, Tuesday. July 20, 2010 34Fig. 15-3, p. 414

Class #10, Tuesday. July 20, 2010 35

Class #10, Tuesday. July 20, 2010 36Fig. 2, p. 425

Class #10, Tuesday. July 20, 2010 37Fig. 3, p. 425

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Class #10, Tuesday. July 20, 2010 39

Some Notable Storms

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

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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

Class #10, Tuesday. July 20, 2010 43Fig. 15-18, p. 428

Class #10, Tuesday. July 20, 2010 44Fig. 15-19, p. 428

Class #10, Tuesday. July 20, 2010 45Fig. 15-20, p. 429

Class #10, Tuesday. July 20, 2010 46Fig. 15-21, p. 429

Class #10, Tuesday. July 20, 2010 47Fig. 15-22, p. 430

Class #10, Tuesday. July 20, 2010 48Fig. 15-22, p. 430

Class #10, Tuesday. July 20, 2010 49Fig. 15-22, p. 430

Class #10, Tuesday. July 20, 2010 50Fig. 15-23, p. 430

Class #10, Tuesday. July 20, 2010 51Fig. 4, p. 431

Class #10, Tuesday. July 20, 2010 52Stepped Art

Fig. 4, p. 431

Class #10, Tuesday. July 20, 2010 53Fig. 15-24, p. 432

Class #10, Tuesday. July 20, 2010 54Fig. 15-25, p. 432

Class #10, Tuesday. July 20, 2010 55Fig. 15-26, p. 433

Class #10, Tuesday. July 20, 2010 56Fig. 15-27, p. 433

Class #10, Tuesday. July 20, 2010 57Fig. 5, p. 434

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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.

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Class #10, Tuesday. July 20, 2010 60Stepped Art

Fig. 15-27, p. 433

Class #10, Tuesday. July 20, 2010 61Fig. 6, p. 434

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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