Hurricanes and Nor’easters (Ch 14)
Hurricanes and Tropical Storms
Well organized large circulating storms that originate over tropical waters.
High evaporation rates and steering winds contribute to storm development.
Tropical Storm Terms
Terminology regional:
Hurricane
in Americas, eastern Pacific;
Typhoon
in Western
Pacific;
Cyclone
in Indian Ocean and Southwest Pacific
Hurricane: 3 Key ingredients
1) Warm ocean water over 80 degrees farenheight is the fuel for the hurricane
2) Favorable winds aloft which allows the hurricane to grow vertically
3) Coriolis effect which provides rotation of the storm
Hurricane energy machine
Hot humid air over warm water 5 degrees to 20 degrees N or S- unstable (less dense
à
moves
upward in atmosphere)
-Rising air cools and condenses- releases latent heat energy (heat
à
phase change of liquid to
gas as water evaporated)
-More rising, condensing, latent energy release
-Continues to organize *atmospheric pressure goes down and wind speeds increase) as
convection extends upward
-Rotation of inflowing air improves circulation
-Central part is called eye and the eyewall is where winds are strongest and at the bottom are
rain bands where the condensation is going on- inside the eye is quiet and very humid and
sticky
What Happens
Rising air and condensation builds into ‘chimney’ of thunderstorms
Warm, moist air rises and spreads at top of chimney
Warm air expands, cools and releases latent heat
Eye of hurricane is as much as 20
o
C warmer than surrounding air
Rising air pulls more air into center of hurricane at low elevations
Convection strengthens when air rises to high altitude without strong winds to shear off
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- Spring '09
- KRUGER
- Storm, tropical storm, Tide
-
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