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Thunderstorms and Tornadoes. Last Lecture: We looked at severe weather events in the lower latitudes Principal weather event is the formation and movement of Tropical Cyclones Today: Today we will look at severe weather in the mid-latitudes Most severe weather is related to thunderstorms
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Thunderstorms and Tornadoes • Last Lecture: • We looked at severe weather events in the lower latitudes • Principal weather event is the formation and movement of Tropical Cyclones • Today: • Today we will look at severe weather in the mid-latitudes • Most severe weather is related to thunderstorms • Significant convection and precipitation • Very strong winds • Produces thunder and lightning • Can also initiate tornados - most intense wind events on planet
Thunderstorms and Tornadoes • Thunderstorms • Cells of local, intense convection resulting in the formation of cumulonimbus clouds, heavy rainfall, lightning and occasionally hail and tornados
Thunderstorms and Tornadoes • Air Mass Thunderstorms • Isolated storms generated by daytime heating of land surface Convection Cell
Thunderstorms and Tornadoes • Severe Thunderstorms • Thunderstorms with high winds, hail and possibly tornados
Thunderstorms and Tornadoes • Mesoscale Convective System • Long-lived, intense cluster of convection cells • Mesoscale Convective Complexes • Large circular complex of thunderstorms active during the night
Thunderstorms and Tornadoes • Squall line • Line of severe thunderstorms and very strong winds
Thunderstorms and Tornadoes • Dry line • Boundary between hot, dry air and warm, moist air, which tends to form squall line
Thunderstorms and Tornadoes • Lightning • electrical discharge producing light from cloud to cloud or cloud to ground • Thunder • sound of rapid expansion & cooling of superheated air around a lightning bolt
Thunderstorms and Tornadoes • Charge Separation • Difference in charge between cloud top and bottom
Thunderstorms and Tornadoes • Lightning stroke • Complex series of processes which produce electrical discharge between cloud and ground • Leader • Channel of ionized air along which lightning stroke propagates
Thunderstorms and Tornadoes • Tornado • Small, intense cyclonic storm characterized by a funnel descending from mesocyclone
Thunderstorms and Tornadoes Wind Shear • Tornado Dynamics Convection
Thunderstorms and Tornadoes Mesocyclone • Tornado Dynamics con’t. Tornado
Thunderstorms and Tornadoes • Tornado Structure
Thunderstorms and Tornadoes • Weather Conditions during Formation Cold front provides Wind Shear Squall Line provides Convection
Thunderstorms and Tornadoes • “Tornado Alley” • Region of the United States with high frequency of tornado occurrence
Thunderstorms and Tornadoes • Fujita Scale • Measure of strength of tornado based upon severity of damage left behind
Thunderstorms and Tornadoes • Detection of Tornado Vortex Signature using Radar Hook Echo