What Are Tornadoes ?

• Tornadoes are columns of violently rotating air developed in a convectional cloud and are in contact with the ground.

• Tornadoes usually occur along with thunderstorms in the spring and summer in the mid-latitudes of the hemispheres.

• Tornadoes are known for generating the strongest winds on the planet.

How Are Tornadoes Formed ?• Prior to a developing

thunderstorm, a change in wind direction and an increase of wind speed with increasing height, forms a horizontal spinning motion.

• Rising air from the thunderstorm updraft tilts the spinning column of air so it is now vertical.

• This “funnel” of air extends down from the cloud towards the ground. When it reaches the ground, a tornado is created.

Conditions Necessary For Tornadoes To Form

• Very warm, humid air

• Very cool, dry air to the west and south

• Front from the west moves and replaces warm moist air

• High in the sky, the warm moist air rises very far, fast

• Upper level wind stream moves air away from rising column

• Warm, wet air driven east by strong cold front

How Do Tornadoes End ?Tornadoes begin to diminish when any of the factors that caused the tornado begin to deteriorate.

Where Do They Occur ?Tornadoes occur along the mid-latitudes of the hemispheres. In Canada we don’t suffer much at all from them, but to the left is a tornado activity map of the United States.

How Are Tornadoes Measured ?

• Tornadoes intensity’s are measured with the Fujita Scale.

• The Fujita Scale was created by a man named Tetsuya “Ted” Fujita,

• (1920-1998)

• This is a picture of Dr. Fujita with his Tornado simulator.

The Fujita ScaleThe Fujita Scale goes from F0 through to F6. F0 being a weak tornado and F6 being a very violent tornado. Here is a chart showing the phrase for each type of tornado, and the wind speed.

F0

F1

F2

F3

F4

F5

F6

Gale Tornado

Moderate Tornado

Significant Tornado

Severe Tornado

Devastating Tornado

Incredible Tornado

Inconceivable Tornado

40-72 mph

73-112 mph

113-157 mph

158-206 mph

207-260 mph

261-318 mph

319-379 mph

Th Fujita Scale 2

Above is a pie graph showing the percentage of all tornadoes that are each intensity class.

Above is a pie graph showing the percentage of death’s caused by different strengths of tornadoes.

The Fujita Scale 3F0- Damage that could be caused by these tornadoes is chimney damage, broken branches, and shallow rooted trees are toppled.

F1-Roof surfaces peeled off, broken windows, snapped tree trunks, trailers could be toppled, attached garage damages.

F2- Roof structures damaged, manufactured homes are destroyed, debris becomes airborne, larger trees snap or become uprooted.

The Fujita Scale 4

F3- Roofs and walls can be torn from structures, small buildings destroyed, many trees throughout forest could be uprooted.

F4-Well constructed houses are destroyed, structures could be lifted from foundations and carried a distance, cars get blown some distance, larger debris becomes airborne.

F5-Strong frame houses are lifted from foundations, reinforced concrete structures are damaged, vehicles become airborne, large trees completely debarked.

Do They All Look Alike ?

No, there are many different shapes and sizes of tornadoes. Above is an example of a “wedge” tornado.

Shelters

In the United States, Tornado Alley to be exact, many homes often have shelters. Shelters are usually small storm cellar-like structures that are usually in ground, but some can be above ground.

Some HistoryThe year 1896 was a record year for killer tornadoes in the united states, having over 40 killer tornadoes including the only tornado ever to kill more than 100 people in two separate cities.

On May 27, 1986 two tornadoes touched down at the same time, but from two different thunderstorms. One of them leveled many farms, and the other was the third deadliest in US history.

It cut a half a mile path through St.Louis, Missouri.

Interesting FactsVery intense tornadoes often have more than one vortex, or funnel moving around the center vortex.

Deadliest Tornado in US HistoryThe deadliest tornado in United States history occured at about 1:01 PM on March 18, 1925.

This tornado set records for speed, path length and death rate.

Tornado SafetyPrior to Storm:

Homes that have had any scare of a tornado should have a practiced plan for a tornado.

There should also be random radio or t.v. checks, just in case.

During a Storm:

Avoid windows and easily breakable objects, stay out of automobiles, move to planned shelter. If you don’t have a storm shelter, move to lowest area possible, under a strong structure.

If your not home:

Avoid being in automobiles and/ or in mobile homes as they can be thrown around.

Also, overpasses are dangerous in tornadoes because wind speeds increase when going under overpass.

Tornado Safety 2

The government does offer aid when it comes to Tornado safety. There is an agency called FEMA or Federal Emergency Management Agency. FEMA provides people in high-risk tornado/hurricane area’s with a lot of information about residential and community shelters.

They help people repair their broken homes and buildings, provide victims shelter, and also they teach people how to be prepared and what to do in the event of a tornado.

Why They Occur in Central US

There is a high rate of tornado occurance in Central United States due to the continental polar air mass from the north merging with the Tropical air from the south.

Two Tornadoes

Funnels That Didn’t Reach The Ground

Devastating Funnels

Bibliographyhttp://www.chaseday.com/tornadoes.htm

http://whyfiles.org/013tornado/index.html

http://www.usatoday.com/weather/tg/wtorwhat/wtorwhat.htm

http://www.tornadoproject.com/safety/shelters.htm

http://rsd.gsfc.nasa.gov/goes/text/hotstuff.html

http://www.stormvideo.com/tornado.html

http://www.mysteries-megasite.com/mysterymovies/tornmovie.html

http://www.fema.gov/mit/saferoom/

http://www.disastercenter.com/tornado.htm

http://teacher.scholastic.com/researchtools/articlearchives/weather/tornado.htm

http://www.tornadoproject.com/fscale/fscale.htm

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http://www.usgs.gov/themes/animationmap.html