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Tropical Cyclones, Hurricanes, and Typhoons
Winds speeds in excess of 64 knots (74 mph)
Global sea surface temperatures
T > 81 oF=27 °C for hurricane formation
Warm enough ocean temperatures
& large enough Coriolis force
(Latitudes greater than 10 degrees)
Stages in development
Complexes of thunderstorms
>64 knots
20-34 knots
35-63 knots
stages
Tropical Depressions
Initial thunderstorm growth
1. ITCZ
Warm enough ocean temperatures
& large enough Coriolis force
(Latitudes greater than 10 degrees)
Rain Bands
Eye Wall
Eye
The pressure in the eye near the surface is very low and controls
the hurricane’s strength. The pressure high above the surface in
the eye is High cause air to sink and clouds to dissappear.
Surface pressure is lowest in the eye of a hurricane. Wind speed is
maximum in the eye wall and is usually calm in the eye. Intense
rain, winds, and possibly tornadoes are most likely in the eye wall.
Katrina August 28, 2005 TRMM (Tropical Rainfall Measuring Mission)
Climatology
El Nino and Hurricanes
Are hurricanes getting more frequent or more intense?
Red-total hurricanes and tropical storms (named storms)
Yellow : total hurricanes
Green : cat 3 or above
Total power dissipated by hurricanes PDI seems to be increasing since 1980.
From: http://www.pbs.org/wgbh/nova/earth/stronger-hurricanes.html
And
http://www.pbs.org/wgbh/nova/sciencenow/3302/07-hott-nf.html
Most recent data.