GEOG 1290 Lecture Notes - Lecture 23: Tropical Cyclone, Wind Shear, Lightning
29 Nov 2014
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Document Summary
Convergence behind wave, divergence ahead of wave. Introduction: steep pressure gradient, intense low pressure tropical cyclones. Regional names: typhoons (western north pacific, cyclone (indian ocean, hurricane (n. america. Tropical disturbances: tropical depression <33 knots, <60km/h, tropical storm 34-63 knots, 60-116 km/h, tropical cyclone (hurricane) >60 knots, 120 km/hr. Cyclonic convergence: energy source and release. Storm pulls in warm, moist air for fuel, causing updrafts in the clouds. Cools adiabatically and causes rain and latent heat release (more instability) adds power: eye: non-stormy center, no updrafts (downdrafts, near top of the storm: air diverges into upper troposphere (except in eye, where there"s a downdraft. Origin: warm tropical waters, coriolis effect is minimized near the equator so no hurricanes form there. None observes within 3 degrees n/s of equator. Most originate pole ward side of itcz: easterly waves. Hurricanes only form if no wind shear in troposphere. Wind shear: significant change in direction and/or speed with changing elevation.
