This is the time of year tornadoes are most likely to erupt, so we called John Knox, one of the tornado experts in the University of Georgia’s atmospheric sciences program, to separate fact from fiction about tornadoes and surviving them.
1. TORNADOES CAN CLIMB MOUNTAINS. TRUE.
Some people believe that tornadoes won’t cross rivers, or that a mountain will protect a city. Tornadoes happen in the mountains, too, said Knox; one was spotted in the Smoky Mountains during the 2011 tornado outbreaks.
2. TORNADOES HAPPEN ONLY DURING SPRING. FALSE.
Tornadoes are more likely in spring, especially April. But twisters can form in any month. In fact, there’s a kind of secondary peak in November and December, Knox said.
“Mother Nature does not check the calendar and say, ‘I have all the ingredients here, but it’s not spring,’” he said.
The conditions are more likely in spring, but the factors that cause a tornado ‑ a lifting air pattern, moist air and a jet stream to impart spin ‑ can come together any time.
3. YOU SHOULD SHELTER IN THE SOUTHWEST CORNER OF YOUR HOUSE DURING A TORNADO. FALSE.
“When I was a kid, I was told to open the windows and hide in the southwest corner of the basement. That’s 100 percent wrong,” Knox said. “In reality, the place where you’re supposed be is the center of the house, on the lowest level, and with as many walls as possible between you and the outside.”
Tornado winds aren’t as strong at ground level as they are even 20 to 30 feet higher up.
Opening windows is an equally bad move.
“The idea was to equalize air pressure,” Knox said.
But unless you live in an absolutely airtight house, that strategy won’t work — not that it would anyway.
“What really happens is that you actually help the storm rip your house apart,” he said.
And stay away from those windows, he said.
“You just shouldn’t be near a window. ‘The Wizard of Oz’ got it right,” he said, referencing the mad dash to the cellar.
4. TAKE REFUGE UNDER AN OVERPASS. FALSE.
“That was a myth propagated in the 1990s that’s still out there,” Knox said.
But an elementary principle of physics explains why it’s a bad idea.
“Overpasses channel the wind, and when you constrict flow, it goes faster,” he said.
5. TORNADOS CAN PICK PEOPLE UP AND SET THEM DOWN UNHARMED SOMEWHERE ELSE. FALSE.
“Chickens have survived tornadoes,” he said. “People tend to get head injuries.”
For the most part, tornadoes cannot pick up heavy objects and carry them a long way.
“If (the object is) shaped like an airfoil, it can go a long way,” he said.
In one exceptional instance during the 2011 tornado outbreak that devastated parts of Alabama, a 5-foot sign wound up 50 miles away. But tornadoes can carry lighter objects many miles, Knox and his students found in a study of that 2011 Alabama tornado outbreak; one photograph traveled 219 miles.
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