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Tornado!Introduction to Lesson 37

“Warning Signs'

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Ben Franske

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What is a tornado?

A tornado is a violent, dangerous, rotating column of air that is in contact with both the earth and a cloud. Sometimes they are called

twisters.

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Where do tornados occur?

They have been reported on every continent except Antarctica, but the vast

majority of them occur in the United States in what is known as Tornado Alley, an area recognized as being generally between the

Rocky Mountains and the Appalachian Mountains.

Texas reports the most tornados. Next is Kansas, then Oklahoma.

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Juerg

en P

ohl

Germany

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Daphne Z

ara

s

Oklahoma

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Binger, OklahomaWedge Tornado, almost a

mile wide

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RopingTornado

Oklahoma

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Oklahoma

This is the same tornado seen at about the same time.

In top frame, the sun is behind the camera, shining toward the

tornado and causing it to appear bluish.

In the bottom frame, we are looking at the tornado from the opposite direction, with the sun behind the tornado which makes

it appear dark.

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Alabama

Frank

Pete

rs

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Texas

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Multivortex tornado in Dallas, Texas

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Birth of a TornadoTexas, 1995

In first frame, rotating cloud base lowers

In second frame, lowering clouds become a funnel,

with winds kicking up dust and debris

In third frame, touchdown!

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California

Jonath

an N

afa

rrete

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Lisa

Jaco

bs

Massachusetts

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Alabama

JLS Media

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ArizonaDust devil

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Waterspout Florida Keys

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Salt Lake City, Utah

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Connecticut

Russ Glasson

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Connecticut

Russ Glasson

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Ringgold, Georgia, 2011

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Tornado Warning!

Ben Franske

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Tornado MythsA green sky indicates a possible tornado. (A green sky can be associated with severe weather but is not specifically linked with tornadoes.)

Opening windows will lessen the damage caused by a tornado. (While there is a large drop in atmospheric pressure inside a strong tornado, it is unlikely that the drop would cause a house to explode, and it is possible that opening windows increases damage rather than lessens it.)

Highway overpasses provide adequate shelter from a tornado. (A highway overpass is a dangerous place to be during a tornado. They can be directly struck by a tornado and when this happens, a fatality is likely to occur.)

The southwest corner of a basement provides the most protection from a tornado. (The safest place is the side or corner of an underground room opposite the tornado’s direction of approach or the central-most room on the lowest floor.)

A major river or being up against a hill or mountain offers protection during a tornado. (Tornadoes have crossed major rivers and climbed mountains.)

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How To Be Safe

Though tornadoes can strike in an instant, you can increase the chances of surviving a tornado. When a warning is issued, going to a basement or an interior first-floor room of a sturdy building greatly increases chances of survival. In tornado-prone areas, many

buildings have storm shelters on the property. These underground refuges have saved thousands of lives.

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If driving on the road when a tornado approaches, it is advised that drivers park their vehicles far to the side of the road (so as not to block emergency traffic) and find

a sturdy shelter. If no sturdy shelter is nearby, getting low in a ditch is the next best option. Highway overpasses are one of the worst places to take shelter during

tornadoes, as they are believed to create a Venturi effect, a term that describes the

increased danger from the tornado by the increased wind speed and funneled debris

underneath the overpass.

Next is a picture of a sturdy building.

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Alabama 2011 Tornado

WildBamaBoy

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Video of the Billings, Montana, tornado is at:

http://www.wtsp.com/news/topstories/story.aspx?storyid=134544

And a gallery of pics can be seen at:

http://download.gannett.edgesuite.net/wtsp/webgallery/2010/billings-montana-tornado/index.htm#1