Tornados

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Slide 1

TORNADOS

Slide 2

Do Tornados Really Sound Like Freight Trains??

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

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

Slide 3

Tornado Facts

Winds can exceed 300 mph!!!

Around 1,000 occur on average each year in the U.S.

Kill 80, injure 1,500 people each year on average

Can have a path up to a mile wide!!!

Can occur any time of the year, but peak during the spring (March-June)

Occur most frequently in the central U.S. in a region nicknamed “Tornado Alley”

Slide 4

What Exactly Is A Tornado?

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

Slide 5

How Do They Form?

Actually, no one knows for sure!

But…We have a pretty good idea…

Slide 6

Step 1

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

Slide 7

Step 2

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

Slide 8

Step 3

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

Slide 9

Convection Demo

Same basic principle behind a tornado vortex (funnel; column of fire in this case)

Warm air moves up the vortex (updraft)

Cools and sinks as it funnels out of the top (downdraft)

The more air drawn in = faster and tighter spin

This is called a convection cycle

Slide 10

How Strong Are Tornados?

Strength is measured by the Fujita Scale .

F0 = weakest, F5 = Strongest

Slide 11

Are Most Tornados Strong?

All tornados are potentially deadly, but most are actually relatively weak (74%)…!

Only 1% of all tornados fall in the F4 – F5 range

Slide 12

What’s Up With Xenia, OH?