Download Tornado Alley

Text Book : Pages 450 - 459
A violent disturbance in the atmosphere.
Involves sudden changes in air pressure
Cause rapid air movement
Conditions that bring one kind of storm
in one area often cause other kinds of
storms in the same area
• Thunderstorms
• Tornadoes
• Snowstorms
• Hurricanes
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Torrential Downpours
Strong winds at greater than 58 mph
Hail ¾ inch diameter (or larger)
Frequent lightning
• Issued by National Weather Service
• This means that conditions are favorable for
a thunderstorm
• Length is multiple hours.
• Issued By Local Weather Service
• Means a severe storm has been spotted by
doppler radar
• Usually only an hour
• A sudden spark or
energy discharge,
caused when
electric discharges
jump between parts
of a cloud, nearby
clouds, or between
a cloud and the
ground.
• Because light travels
much faster than
sound.
• Stay indoors, away from doors and windows.
• Avoid objects that conducts electricity, such as metal
objects and bodies of water.
• Do not seek shelter under the trees.
• Do not use phones with cords.
Remember: Cars are pretty safe…
Tornado Alley
A tornado is a rapidly
whirling, funnel shaped
cloud that reaches down
from a cloud to touch
Earth’s surface.
Same system that
produces thunderstorms
can produce tornadoes.
Late in the day, when
earth’s surface is very
warm, convection (the flow
of heat through a
material, causing hot
parts to rise and cooler
parts to sink) can get very
strong. This can lead to a
tornado.
• Conditions are favorable for a tornado to
form
• A tornado has formed.
Tornado Happenings
1. When the
updraft in a
convection cell is
really strong, the
air rushes in
from all sides at
high speeds.
Tornado Happenings
2. Air curves into a spin. This
lowers the pressure even more.
Air rushes in even faster, and
the pressure gets even lower,
and so on.
Like a skater who pulls her arms in close to
her sides. The tornado spins faster and
faster.
Tornado Happenings
3. As the tornado gets stronger, a
funnel forms that can destroy
anything in it’s path. The center of
the tornado can reach speeds of
500 kilometers per hour (about 300
miles per hour) or more.
Where Do Tornadoes
Happen?
Tornadoes happen where dry, cold air
masses mix with warm, moist air
masses.
More tornadoes occur in the United
States than in any other country,
especially in the area known as
TORNADO ALLEY.
A Famous Tornado
Grand Island, Nebraska
June 3, 1980
On June 3, 1980, a series of tornadoes
devastated the city of Grand Island,
Nebraska. Seven tornadoes hit within a
three hour period. The storm did
massive damage and closed the city
down for three days.
All year round, most precipitation
begins in clouds as snow.
If the air is colder than 0 degrees
all the way to the ground, the
precipitation falls as snow.
• Try to find a shelter from the wind.
• Cover exposed parts of your body and try to
stay dry.
• A tropical storm that has winds of about 119
kilometers per hour or higher (200 miles per
hour).
• Storm usually doesn’t last for more than 7-10
days.
• As it moves inland it continues to move across the
land but it begins to weaken
Map Symbols
Intertropical Convergence Zone
The ITCZ is an area of low pressure located roughly 5 degrees North
and South of the Equator. It is a place where air converges, rises, and
condenses (forming clouds). It is the rainiest place on Earth!
So What Does a Hurricane Need in Order to Develop?
So a hurricane needs warm water, time to grow, and favorable upper
level winds in the troposphere. If the winds are too strong, they will
blow the hurricane apart – we call that wind shear!
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A list of names from A-W (excluding Q)
Alternate from male to female
6 lists, repeated in cycle
Big name storms replaced
• A hurricane poses a possible threat within
the next 36 hours
• Hurricane conditions expected within 24
hours
The Saffir-Simpson Scale
http://www.nhc.noaa.gov/aboutsshws
.php
Saffir-Simpson Wind Scale
and Animations
http://www.nhc.noaa.gov/surge/
Storm Surge Overview and
Animations
Category
Wind Speed
1
74-95 mph
2
96-110 mph
3
111-129 mph
4
130-156 mph
5
157 mph or greater
• Best plan is to evacuate
– Towns have voluntary evacuation during a
watch, and some switch to mandatory during a
warning.
• Plan early in advance
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Board all windows
Prepare Flashlights, avoid candles
Stay tuned to radio
Stay indoors