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Chapter 8
Weather
Robert W. Christopherson
Charlie Thomsen
Weather Forecasting
Figure 8.17
Violent Weather
Thunderstorms
Tornadoes
Tropical Cyclones
Thunderstorms: cumulonimbus clouds create heavy
precipitation, lightning, thunders, hail, wind and tornadoes
Florida has the
highest frequency
of T-storms
Figure 8.19
Thunderstorms
Figure 8.20
Lightning: flashes of light caused by
enormous electrical discharges (10-100
millions of volts, super heat the air to 1500030000ºC)
Thunder: violent expansion of air sends shock
waves through atmosphere
Lightning hazards: people, animals. Trees,
and structures. About 200 death and
thousands of injuries in US and Canada
Hailstones
Figure 8.21
Mesocyclone and
Tornado
Figure 8.22
Tornado: funnel
clouds touch the
earth’s surface;
a few meter to
100m in size; Its
intensity is
measured by
Fujita scale
Figure 8.22
Tornado
Figure 8.22
Super Cell
Tornado
and
Eye
Wall
Figure 8.23
Tornado Path
Figure 8.22
Tornadoes: spatial and temporal distribution
Tornado Alley: Texas, Oklahoma, Kansas.
Peak season: May and June in United States
Figure 8.24
Tropical storms start in
easterly waves.
Easterly Waves: waves
move from east to west,
thunderstorms occur
over the east side of the
trough
Figure 8.25
Tropical Cyclones
Figure 8.26
Hurricanes Gilbert and Catarina
Hurricane: tropical
cyclone when its
maximum wind
speed exceed 65
knots (119kph,
74mph)
Figure 8.26
Profile of a Hurricane
Eyewall: vertical rising air, thick
clouds, strong wind
Eye in the center (clear sky, calm)
Figure 8.27
Hurricane Isabel,
Cape Hatteras
and the
Outer Banks
Figure 8.28
2005: Record-Breaking Storm Season
Hurricane season is during later summer and early fall
Requirements: warm surface water temperature, 5º away from equator
Figure FS 8.1.1