Thermodynamics of Thermodynamics of Tornadoes and HurricanesTornadoes and Hurricanes

Daniel CrnkovichDaniel Crnkovich24 November 200924 November 2009

Tornadoes and HurricanesTornadoes and Hurricanes TornadoesTornadoes

Form over landForm over land If a tornado forms over water it becomes a cycloneIf a tornado forms over water it becomes a cyclone Damage due to windDamage due to wind Scaled from F0 – F5 (Fujita Scale)Scaled from F0 – F5 (Fujita Scale)

HurricanesHurricanes Form over waterForm over water Starts a tropical depression or stormStarts a tropical depression or storm Damage due to waterDamage due to water Scaled from 1 – 5 (Simpson Scale)Scaled from 1 – 5 (Simpson Scale)

Both are hard to predict and cause extensive Both are hard to predict and cause extensive damagedamage

Causes of Hurricanes and TornadoesCauses of Hurricanes and Tornadoes Coriolis ForceCoriolis Force

Inertial force of the EarthInertial force of the Earth Angular MomentumAngular Momentum Air factorsAir factors

Temperature differenceTemperature difference Pressure differencePressure difference

Water factorsWater factors Temperature differenceTemperature difference

Colliding pressure frontsColliding pressure fronts

Thermodynamics of a Thermodynamics of a HurricaneHurricane

Hurricanes modeled by the Hurricanes modeled by the Carnot CycleCarnot Cycle Isothermal expansion (3-4)Isothermal expansion (3-4)

Formation of eyeFormation of eye Increase in entropyIncrease in entropy Driving force of stormDriving force of storm

Adiabatic expansion (3-4)Adiabatic expansion (3-4) Air rises to top of eye wallAir rises to top of eye wall Lower P and TLower P and T

Isothermal compression (4-1)Isothermal compression (4-1) Cloudy air travels to edge of Cloudy air travels to edge of

hurricane (about 200 miles)hurricane (about 200 miles) Decrease in entropyDecrease in entropy

Adiabatic compression (1-2)Adiabatic compression (1-2) Return to original stateReturn to original state

Thermodynamics of a Thermodynamics of a TornadoTornado

Warm and moist air massWarm and moist air mass Lead eastward-moving cold Lead eastward-moving cold

frontsfronts Common in the springCommon in the spring

No thermodynamic model No thermodynamic model has been found for has been found for tornadoestornadoes

Often influenced by particle Often influenced by particle charges differencescharges differences Physics basedPhysics based

Predicting Hurricanes and TornadoesPredicting Hurricanes and Tornadoes Hurricanes take time to formHurricanes take time to form

Succession of tropical depression, storm, Succession of tropical depression, storm, strengtheningstrengthening

Weaken due to landWeaken due to land Once formed, predicting the path can be difficultOnce formed, predicting the path can be difficult

Tornadoes form quicklyTornadoes form quickly Super-cell thunderstormsSuper-cell thunderstorms ““Tornado alley”Tornado alley” Warm and moist air masses followed by cold frontsWarm and moist air masses followed by cold fronts

Future technologies may help in predictionsFuture technologies may help in predictions

Questions?Questions?

Photos courtesy: google.com; NASA; NOAA

Sources: NASA; NOAA; auf.asn.au; charles-chandler.org/Geophysics/Tornadoes Full.php