Hurricanes and Tornadoes Tornadoes Tornadoes are a violently whirling column of air usually seen as a funnelshaped cloud extending from the base if a thunderhead Tornadoes Tornadoes May be 3m to 3km across ID: 514010
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Slide1
Severe Weather
Hurricanes and TornadoesSlide2
Tornadoes
Tornadoes are a violently whirling column of air, usually seen as a funnel-shaped cloud extending from the base if a thunderheadSlide3
Tornadoes
TornadoesMay be 3m to 3km across
Tornado Alley runs from Texas to Michigan
US averages more than 800 a year
Usually last a few minutes
Very destructive
Winds can be more
than 400 km/hSlide4
Average tornado frequency by month of year 2003-2005Slide5Slide6
Fujita Scale
SCALE
WIND ESTIMATE (MPH)
TYPICAL DAMAGE
F0
< 73
Light damage.
Some damage to chimneys; branches broken off trees; shallow-rooted trees pushed over; sign boards damaged.
F1
73-112
Moderate damage.
Peels surface off roofs; mobile homes pushed off foundations or overturned; moving autos blown off roads.
F2
113-157
Considerable damage.
Roofs torn off frame houses; mobile homes demolished; boxcars overturned; large trees snapped or uprooted; light-object missiles generated; cars lifted off ground.
F3
158-206
Severe damage.
Roofs and some walls torn off well-constructed houses; trains overturned; most trees in forest uprooted; heavy cars lifted off the ground and thrown.
F4
207-260
Devastating damage.
Well-constructed houses leveled; structures with weak foundations blown away some distance; cars thrown and large missiles generated.
F5
261-318
Incredible damage.
Strong frame houses leveled off foundations and swept away; automobile-sized missiles fly through the air in excess of 100 meters (109 yds); trees debarked; incredible phenomena will occur.Slide7
Hurricanes
Hurricanes need warm tropical oceans, moisture and light winds above them.
If the right conditions last long enough, a hurricane can produce violent winds, incredible waves, torrential rains and floods
.
Also called Typhoons or Cyclones Slide8Slide9Slide10Slide11Slide12
Stages of Development
Strong Storm
Depression
Tropical Storm
Hurricane Slide13
Saffir-Simpson Hurricane Damage-Potential Scale
Scale Number
Category
Central Pressure
mb
inches
Wind Speeds
mi/hr
knots
Storm Surge
feet
meters
Observed
Damage
1
>=980
>=28.94
74-95
64-82
4-5
~1.5
some damage to trees, shrubbery, and unanchored mobile homes
2
965-979
28.50-28.91
96-110
83-95
6-8
~2.0-2.5
major damage to mobile homes; damage buildings' roofs, and blow trees down
3
945-964
27.91-28.47
111-130
96-113
9-12
~2.5-4.0
destroy mobile homes; blow down large trees; damage small buildings
4
920-944
27.17-27.88
131-155
114-135
13-18
~4.0-5.5
completely destroy mobile homes; lower floors of structures near shore are susceptible to flooding
5
<"920"
<"27.17"
>"155"
>"135"
>"18"
>"5.5"
extensive damage to homes and industrial buildings; blow away small buildings; lower floors of structures within 500 meters of shore and less than 4.5 m (15 ft) above sea level are damaged