Making
aTwister
Tornadoes are produced inside powerful thunderstorms, which in turn are created near the junction between warm/moist air and cold/dry air. And that gives us a clue to the major source of their energy: the latent heat (defined) contained in the warm, moist air mass.
- One section of the nation is best at producing tornadoes.
This area is called "Tornado Alley," (shown on the map). Tornadoes
are also relatively common in Alabama, Arkansas, Florida, Georgia, Illinois,
Indiana, Iowa, Kansas, Louisiana, Mississippi, Missouri, Nebraska, Oklahoma,
South Dakota, and Texas. Twisters are most common in spring and summer.
Nature creates its most powerful tornadoes by creating an atmospheric sandwich. This forms when moist, warm air gets trapped beneath a stable layer of cold, dry air. It is held there by an intervening layer of warm, dry air called an inversion or 'cap.'
If a front or disturbances in the upper atmosphere move in, they help the warm, moist air break free. This air can rise and punch through the stable-air cap that was holding it down.
The warm air will start to spiral upward, as latent heat is released when the moisture it holds condenses. Aided by different winds at different levels of the atmosphere, the rotating updraft gains velocity. That, much simplified, is the origin of a tornado.
Next: Tornado Breeding Ground.
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