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Tornadoes are one of nature's most violent storms. In an average year, about
1,000 tornadoes are reported across the United States, resulting in 80 deaths and over 1,500 injuries. A tornado is a violently
rotating column of air extending from a thunderstorm to the ground. The most violent tornadoes are capable of tremendous destruction
with wind speeds of 250 mph or more. Damage paths can be in excess of one mile wide and 50 miles long.
Tornadoes come in all shapes and sizes and can occur anywhere in the U.S. at any time
of the year. In the southern states, peak tornado season is March through May, while peak months in the northern states are
during the summer.
Tornadoes are one of those amazing, awesome acts of nature that simply leaves you dumbfounded -- a huge, swirling, 200-mph
beast of a storm that appears to have a mind of its own. You have to actually see one with your own eyes to believe it. In
certain places, tornadoes appear with amazing regularity. That's why we see them in the news all the time.
In this article, we will take a look at tornadoes to learn what they are, how they form and just how powerful they can
be.
Tornadoes and Your Bathtub
If you have ever seen a whirlpool form in your bathtub,
sink or toilet when the water is draining, you have seen the fundamentals of a tornado at work. A drain's whirlpool, also known as a vortex,
forms because of the downdraft that the drain creates in the body of water. The downward flow of the water into the drain
begins to rotate, and as the rotation speeds up the vortex forms.
Vortex
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Why should the water start rotating? There are lots of explanations, but here is one way to think about it (and this way
happens to apply to black holes as well as it does to drains). Imagine you are a particle in the water, and you are being pulled toward the suction that
the drain creates. You are accelerating toward the point of suction. However, because of your previous momentum, the number
of other particles getting sucked toward the point and other factors, chances are that you are going to be off to one side
of the point of suction when you arrive. That deflection sets you up on a spiraling path into the point of suction,
like a moth spiraling in toward a light. Once the spiral has started in one direction, it tends to influence all of the other
particles as they arrive. A very strong spiraling tendency is created. Eventually, there is enough spiraling energy to create
a vortex.
Given that you see vortexes all the time in tubs and sinks, it is obviously a fairly common phenomenon. In a tornado, the
same sort of thing happens, except with air instead of water.
Tornadoes and Thunderstorms
With a tornado there is no drain. Instead, there is
a thunderstorm cloud. A typical thunderstorm cloud can accumulate a huge amount of energy. If the conditions
are right, this energy creates a huge updraft into the cloud. But where does the energy come from?
Clouds are formed when water vapor condenses in the air. This change in physical state releases heat, and heat is a form
of energy. A good deal of a thunderstorm's energy is a result of the condensation that forms the cloud. According to Encyclopedia Britannica:
For every gram of water condensed, about 600 calories of heat are made available. When the water freezes in the upper
parts of the cloud, another 80 calories of heat per gram of water are released. This energy goes to increase the temperature
of the updraft and, in part, is converted to kinetic energy of upward and downward air movement. If the quantity of water
that is condensed in and subsequently precipitated from a cloud is known, then the total energy of a thunderstorm can be calculated.
In an average thunderstorm, the energy released amounts to about 10,000,000 kilowatt-hours, which is equivalent to a 20-kiloton
nuclear warhead. A large, severe thunderstorm might be 10 to 100 times more energetic. In supercell thunderstorms,
the updrafts are particularly strong (see the links at the end of this article for information on supercells).
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