ATOC 185 Lecture Notes - Lecture 6: Vertical Draft, Supercell, Thunderstorm
22 Feb 2017
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Document Summary
A violent rotation column of air in the atmosphere which is in contact with the ground. Tornadoes form from rotating supercell thunderstorms caused by a mid-latitude low pressure system. Tornadoes are small and stay in one area. Most people in a storm prone to tornadoes will never see a tornado. Mid-latitude low pressure storm system: spreads over 15 km, rotating slowly. Tornadoes: rotates very quickly, has a small spread area. To generate a tornado: instability is needed to create rapid rising motion of wind, a trigger to initiate rising motion in the atmosphere, wind shear to create a spin necessary for a rotating thunderstorm. In both cases, the warm air will rise towards the colder air above. Both need a trigger: a organised atmosphere region of rising air. For a hurricane: you need a cold front in the tropics, easterly waves and intertropical convergence zones.
