1. Thermodynamics of Tornadoes and Hurricanes Daniel Crnkovich 24 November 2009

2. Tornadoes and Hurricanes • Tornadoes • Form over land • If a tornado forms over water it becomes a cyclone • Damage due to wind • Scaled from F0 – F5 (Fujita Scale) • Hurricanes • Form over water • Starts a tropical depression or storm • Damage due to water • Scaled from 1 – 5 (Simpson Scale) • Both are hard to predict and cause extensive damage

3. Causes of Hurricanes and Tornadoes • Coriolis Force • Inertial force of the Earth • Angular Momentum • Air factors • Temperature difference • Pressure difference • Water factors • Temperature difference • Colliding pressure fronts

4. Hurricanes modeled by the Carnot Cycle Isothermal expansion (3-4) Formation of eye Increase in entropy Driving force of storm Adiabatic expansion (3-4) Air rises to top of eye wall Lower P and T Isothermal compression (4-1) Cloudy air travels to edge of hurricane (about 200 miles) Decrease in entropy Adiabatic compression (1-2) Return to original state Thermodynamics of a Hurricane

5. Warm and moist air mass Lead eastward-moving cold fronts Common in the spring No thermodynamic model has been found for tornadoes Often influenced by particle charges differences Physics based Thermodynamics of a Tornado

6. Predicting Hurricanes and Tornadoes • Hurricanes take time to form • Succession of tropical depression, storm, strengthening • Weaken due to land • Once formed, predicting the path can be difficult • Tornadoes form quickly • Super-cell thunderstorms • “Tornado alley” • Warm and moist air masses followed by cold fronts • Future technologies may help in predictions

7. Questions? Photos courtesy: google.com; NASA; NOAA Sources: NASA; NOAA; auf.asn.au; charles-chandler.org/Geophysics/Tornadoes Full.php