Let’s learn about tornadoes

Tornadoes are violently rotating columns of air that can carve a path of destruction a mile wide

More than 1,000 tornadoes strike the United States each year — particularly in an area of the U.S. Great Plains nicknamed “Tornado Alley.”

Jason Persoff Stormdoctor/Getty Images

Tornadoes are some of the world’s most fearsome weather events. These violently spinning columns of air can fling aside cars and flatten houses. The biggest ones can carve a path of destruction 1.6 kilometers (1 mile) wide. And they can tear across more than 160 kilometers (100 miles) before winding down. Some last mere minutes. Others roar on for more than an hour.

Tornadoes tend to emerge from thunderstorms called supercells. In these storms, chaotic winds can churn air into a horizontally rotating tube. A strong upward surge of air can then tilt that tube to spin vertically. Under the right conditions, that eddy of air can give rise to a tornado. It’s generally thought that tornadoes snake down from the clouds to touch the ground. But some tornadoes may in fact form from the ground up.

Storms whip up tornadoes around the world. But the United States sees more of these events than any other country, averaging more than 1,000 tornadoes each year. Many of these whirlwinds tear through a swath of the Great Plains nicknamed “Tornado Alley.” States in this region include Nebraska, Kansas and Oklahoma. All 50 states, though, have had tornadoes touch ground at some point.

Weather experts rate tornadoes’ destructive power from 0 to 5 on the Enhanced Fujita (EF) Scale. Level-0 tornadoes have winds of 105 to 137 kilometers (65 to 85 miles) per hour. This might damage trees. Level-5 twisters blow away whole buildings. They have winds stronger than 322 km/hr (200 mi/hr). And stronger tornadoes are getting more common. The reason may be human-caused climate change. In a warmer world, the atmosphere holds more heat and moisture to fuel monster tornadoes.

Climate change is revving up other disasters that can spawn tornadoes, too. Among these are hurricanes and wildfires. The bluster of a tropical storm can spin out dozens of tornadoes. Hurricane Harvey, for instance, spawned more than 30 tornadoes in Texas in 2017.

Tornadoes born of wildfires, on the other hand, are extremely rare. Only a few such “firenadoes” have ever been recorded. The first was in Australia in 2003. Another arose in the deadly Carr Fire in California in 2018.

Sharknados, of course, are complete fiction. But plenty of other water-dwelling critters have been documented getting pulled up into the sky by powerful storm — only to rain down later. So next time it’s raining “cats and dogs,” be grateful it’s not literally raining frogs and fish.

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Hurricane Harvey proved to be a tornado master Hurricane Harvey and other tropical cyclones sometimes spawn tornadoes by the dozens. And these tropical storms don’t need the typical recipe to let twisters loose. (9/1/2017) Readability: 7.4

California’s Carr Fire spawned a true fire tornado In July 2018, California’s deadly Carr Fire unleashed an amazingly rare “firenado.” (11/14/2018) Readability: 7.6

New research may alter what we know about how tornadoes form Many people picture tornadoes forming from funnel clouds that eventually extend to the ground. But twisters may not always form from the top down. (1/18/2019) Readability: 7.8

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Activities

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Use NOAA’s tornado simulator to see the damage that twisters of different intensities can do. Dial up or down a virtual tornado’s width and rotation speed. Then hit “Go!” to watch the havoc your custom-made tornado can wreak on a single house.

Maria Temming is the assistant editor at Science News for Students. She has bachelor's degrees in physics and English, and a master's in science writing.

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