Transcript Tornadoes - St. Ann Catholic School

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How does the weather system form?
Where does it form?
When (what time of year) does it occur?
What are the effects of it?
Why is it considered dangerous?
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A violent rotating column of air
extending from a thunderstorm
to the ground.
Warm moist air from the Gulf,
and cold, dry air from Canada—
instability is the result
form in areas where winds at
all levels of the atmosphere are
not only strong, but also turn
with height in a clockwise or
veering direction.
Fujita Scale of Tornado Intensity
SCA
WIND SPEED POSSIBLE DAMAGE
LE
F0
40-72 mph
F1
73-112 mph
F2
113-157 mph
F3
158-206 mph
F4
207-260 mph
F5
261-318 mph
Light damage: Branches broken off trees;
minor roof damage
Moderate damage: Trees snapped; mobile
home pushed off foundations; roofs
damaged
Considerable damage: Mobile homes
demolished; trees uprooted; strong built
homes unroofed
Severe damage: Trains overturned; cars
lifted off the ground; strong built homes
have outside walls blown away
Devastating damage: Houses leveled leaving
piles of debris; cars thrown 300 yards or
more in the air
Incredible damage: Strongly built homes
completely blown away; automobile-sized
missiles generated
Enhanced,
Operational
Fujita Scale
EFO
65-85 mph
EF1
86-110 mph
EF2
111-135 mph
EF3
136-165 mph
EF4
166-200 mph
EF5
over 200 mph
Can be 600 miles across, winds 75 to
200 mph, last for about a week.
rotate in a counter-clockwise
direction around an "eye" in the
Northern Hemisphere and clockwise
direction in the Southern Hemisphere
center of the storm or "eye" is the
calmest part
only form over really warm ocean
water of 80°F or warmer
atmosphere (the air) must cool off
very quickly the higher you go
wind must be blowing in the same
direction and at the same speed to force
air upward from the ocean surface
produced by a cumulonimbus cloud,
usually producing gusty winds, heavy
rain and sometimes hail
basic ingredients used to make a
thunderstorm are moisture, unstable air
and lift (from fronts, seabreezes, or
mountains)
most likely to happen in the spring
and summer months and during the
afternoon and evening hours
Every thunderstorm produces
lightning, which kills more people each
year than tornadoes.
A severe thunderstorm has damaging
winds of 58 miles per hour or more, or
hail three-fourths of an inch in diameter
or greater
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sudden flooding that occurs when floodwaters rise rapidly with no
warning within several hours of an intense rain.
slow moving thunderstorms
the #1 weather-related killer in the U.S.
Nearly 80% of flash flood deaths are auto related.
2 feet of water can float a large vehicle or even a bus
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Winter storms usually form when an air mass
of cold, dry, Canadian air moves south and
interacts with a warm, moist air mass moving
north from the Gulf of Mexico.