Chapter 15

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

Hurricane Formation and Dissipation  The Right Environment Tropical waters with light wind 26.5°C sea surface temperatures (June- November) Surface converge trigger (tropical wave) Coriolis effect: 5-20º latitude  The Developing Storm Cluster of thunderstorms around a rotating Low pressure Release of latent heat, divergence aloft

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)

Hurricane Formation and Dissipation  Topic: Hurricanes and Mid-latitude Storms Hurricane warm core low Mid-latitude cold-core low Arctic hurricanes Hurricane + upper level trough = mid-latitude cyclone  Hurricane movement General track: west, northwest, northeast Much variation

Stepped Art Fig , 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

Some Notable Storms  Camille 1969  Hugo 1989  Andrew 1992  Ivan 2004  Katrina 2005

Some Notable Storms  Observation: Atlantic Hurricanes Abnormally warm ocean water and weak vertical sheer allowed for high frequency of hurricanes  Environmental Issue: Hurricanes in a Warmer World No clear answer, need more data Intensity and frequency most likely to be impacted.

Hurricane Watches, Warnings, and Forecasts  Watch issued 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.

Stepped Art Fig , 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