1

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Twisters Funnel cloud Waterspout

Tornado Nicknames

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A tornado is a violently rotating column of air

extending from a thunderstorm to the

ground

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Cold air from the northWarm air from the Gulf of MexicoChange in wind directionIncrease in wind speedIncreasing heightRising air within a thunderstorm

What Exactly Is A Tornado?What Exactly Is A Tornado?

Violently rotating Violently rotating column of air (Vortex) column of air (Vortex) extending from a extending from a thunderstorm to the thunderstorm to the groundground

How Do They Form?How Do They Form?

Actually, no one knows for sure!Actually, no one knows for sure!

But…We have a pretty good idea…But…We have a pretty good idea…

Step 1Step 1

Before a t-storm, a Before a t-storm, a change in wind change in wind direction and an direction and an increase in speed increase in speed forms an invisible, forms an invisible, horizontal spinning horizontal spinning effect in the lower effect in the lower atmosphere (at the atmosphere (at the base of the storm)base of the storm)

Step 2Step 2

Rising air within the t-Rising air within the t-storm (updrafts) tilts storm (updrafts) tilts the rotating air from the rotating air from horizontal to verticalhorizontal to vertical

Step 3Step 3

Vertical rotation now Vertical rotation now extends 2-6 miles up extends 2-6 miles up into the t-storm. Now into the t-storm. Now a tornado may form a tornado may form and extend from this and extend from this area of rotation to the area of rotation to the ground.ground.

Winds can exceed 300 mph!!!Winds can exceed 300 mph!!! Around 1,000 occur on average each year in the Around 1,000 occur on average each year in the

U.S.U.S. Kill 80, injure 1,500 people each year on Kill 80, injure 1,500 people each year on

averageaverage Can have a path up to a mile wide!!!Can have a path up to a mile wide!!! Can occur any time of the year, but peak during Can occur any time of the year, but peak during

the spring (March-June)the spring (March-June) Occur most frequently in the central U.S. in a Occur most frequently in the central U.S. in a

region nicknamed region nicknamed ““Tornado AlleyTornado Alley””

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Tornado damage is measured by the Fujita

Scale.

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Category Damage Wind

F0 light 40–72 mph

F1 moderate 73–112 mph

F2 significant 113–157 mph

F3 severe 158–206 mph

F4 devastating 207–260 mph

F5 incredible 261–318 mph

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Where do Where do most tornadoes hit in the United States? tornadoes hit in the United States?

In the United States, the area where the tornadoeshit the most is called Tornado AlleyTornado Alley. The

states which are in the tornado alley are:

TexasNebraskaColoradoIowaIllinoisIndianaMissouriArkansas

Danger!Danger! Tornadoes!

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Tornado Watch: A tornado watch is issued when conditionsor the weather is right for a tornado to occur

Tornado Warning: A tornado warning is issued when a tornado has been seen

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Where is the safest place to goduring a tornado?

Basem ent D itch Shower Inner H allway C enter of R oom

Safest P lacesD uring a Tornado

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Number of Tornadoes in Specific Years

0

20

40

60

80

100

120

140

160

180

1979 1985 1992 2004

Tornadoes

Songer http://www.pitt.edu/~super1/lecture/lec0761/005.htm

A Tornado Develops

                                                                                                    

                    

                                                

                                                                             

    

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1. Name at least one tornado nickname.

2. Name one thing needed for a tornado to occur.

3. What is the name of the scale that measures tornadoes?

4. Which state is not in tornado alley: Texas, California, Nebraska, or Kansas?

5. What is it called when conditions are right for a tornado to occur?

6. Where is the safest place to go during a tornado?