Do Tornados Really Sound Like Do Tornados Really Sound Like Freight Trains??Freight Trains??

http://www.interaxs.net/pub/hgr/xenia_tornhttp://www.interaxs.net/pub/hgr/xenia_tornado.mp3ado.mp3

What do you think after listening to the What do you think after listening to the Xenia Tornado of April 3, 1974?Xenia Tornado of April 3, 1974?

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 “Tornado Alley”region nicknamed “Tornado Alley”

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.

Convection DemoConvection DemoSame basic principle behind a tornado Same basic principle behind a tornado

vortex (funnel; column of fire in this case)vortex (funnel; column of fire in this case)Warm air moves up the vortex Warm air moves up the vortex (updraft)(updraft)Cools and sinks as it funnels out of the top Cools and sinks as it funnels out of the top

(downdraft)(downdraft)The more air drawn in = faster and tighter The more air drawn in = faster and tighter

spinspinThis is called a This is called a convection cycleconvection cycle

How Strong Are Tornados?How Strong Are Tornados? Strength is measured by the Fujita Scale...Strength is measured by the Fujita Scale... F0 = weakest, F5 = StrongestF0 = weakest, F5 = Strongest

Are Most Tornados Strong?Are Most Tornados Strong? All tornados are potentially deadly, but most All tornados are potentially deadly, but most

are actually relatively weak (74%)…!are actually relatively weak (74%)…! Only 1% of all tornados fall in the F4 – F5 Only 1% of all tornados fall in the F4 – F5

rangerange

What’s Up With Xenia, OH?What’s Up With Xenia, OH?Xenia has been the target of several major Xenia has been the target of several major

tornados down through the years…tornados down through the years…

Most recent: Sept. 2000 Most recent: Sept. 2000

Most Notable: April 3, 1974 Most Notable: April 3, 1974

Sept. 2000 DamageSept. 2000 Damage

Where do you think this Tornado ranked on the Fujita Scale?

April 3, 1974 TornadoApril 3, 1974 Tornado

April 3, 1974 DamageApril 3, 1974 Damage

Where do you think this tornado ranked on the Fujita Scale?

AnswersAnswers Sept. 2000 = Sept. 2000 = F3-F4F3-F4

(Severe/Devastating (Severe/Devastating Damage; Winds of Damage; Winds of 200-260 mph)200-260 mph)

April 1974 = April 1974 = F5F5 (Incredible Damage; (Incredible Damage; Winds of 260-300+ Winds of 260-300+ mph!!!)mph!!!)

Quick ReviewQuick Review Are most tornados strong or weak?Are most tornados strong or weak? Which would cause more damage, an F1 or an Which would cause more damage, an F1 or an

F5 tornado?F5 tornado? During which season do most tornados occur in During which season do most tornados occur in

the U.S.?the U.S.? What is the nickname of the region in the U.S. What is the nickname of the region in the U.S.

where many tornados occur?where many tornados occur? What is used to classify the intensity of What is used to classify the intensity of

tornados?tornados? Bonus**: How do experts think tornados form?Bonus**: How do experts think tornados form?

THE ENDTHE END

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