Skip navigationTwister: The Tornado Story
 

1. Story map
2. Tornado disaster
3. Interactive twister4. Energetic wind
5. A safe house
6. Twister-in-a-bottle

Q: What's the recipe for becoming a tornado chaser?A: Start with a fascination with intense storms. Add an education in meteorology. Blend in the drive to succeed, add a splash of moxie.

 

 

 

This skinny twister pummeled Boulder, Colo. in June 1997. Photo by Dongsoo Kim, courtesy Forecast Systems Laboratory

 

Spinning Like a Dynamo
A thin, powerful funnel stirs debris into the yellow sky.Energy. Scientifically speaking, it's the ability to do work (that's one of the plainest definitions in science).

This tornado struck Union City, Okla. on May 24, 1973. Photo: NOAA

Energy takes many forms, including chemical, kinetic, potential and thermal. Energy can change forms. You know the drill: Solar energy creates chemical energy in plants, which eventually become petroleum. When your Nash Metropolitan burns gasoline, it becomes heat energy, which then becomes kinetic energy. And when (should we say "if"?) your brakes stop that Nash, the kinetic energy is transformed again into heat energy.

These cows fared better than their barn, after an F2 tornado hit Iron Ridge, Wis. in June 2000. Experts guess this twister blew at 140 to 150 mph. National Weather ServiceCows stand amid wreckage and collapsed fences.

A different set of energy transformations power the furious winds of a twister. Like your car, tornadoes also get their energy from the sun. When the sun warms the ocean, water evaporates and carries potential energy, called the latent heat of vaporization, into the atmosphere. When the water vapor rises, cools and condenses inside a thunderstorm, the latent heat of condensation is released.

According to Robert Davies-Jones of the National Severe Storms Laboratory, this latent heat is the biggest single source of energy in a thunderstorm. When the latent heat is released, it warms the rising air, causing a difference in density that pushes the air up at the extreme speeds needed to create a tornado.

Long, wiry tornado stretches across a story sky toward the ground. Tornadoes release a boatload of energy, says Davies-Jones. A tornado with wind speeds of 200 mph releases kinetic energy at the rate of 1 billion watts -- equal to the electric output of a pair of large nuclear reactors.

But that's just processed cheese compared to the large thunderstorms that can spawn tornadoes. These monsters release latent heat at the rate of 40 trillion watts -- 40,000 times as powerful as the puny twister, Davies-Jones says.

What can all this energy do to your house?

 
 
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The Why Files
  

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