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

20-34 knots

>64 knots

35-63 knots

Complexes of thunderstorms

stages

Tropical DepressionsInitial thunderstorm growth 1. ITCZ

Warm enough ocean temperatures & large enough Coriolis force (Latitudes greater than 10 degrees)

Eye

Eye WallRain Bands

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

Red-total hurricanes and tropical storms (named storms)Yellow : total hurricanesGreen : cat 3 or above

Are hurricanes getting more frequent or more intense?

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.