5 facts about tornadoes, from the Science Storms creator at Chicago’s Museum of Science and Industry

·3 min read

Tornadoes can be scary storms, says senior exhibit developer Olivia Castellini at Chicago’s Museum of Science and Industry, but the more you know about them, the less scary they might seem.

Castellini was the lead creator of Science Storms, an exhibit off the main hall of the museum. Its centerpiece is a 40-foot mock tornado that swirls in a vapor imitation of a funnel cloud and towers over the museum’s main level.

She does not count herself as well-versed in the tornado that hit three southwest suburban communities, including Naperville, late Sunday; the meteorologists who are studying it are the experts, she said. Initial estimates clocked the tornado at wind speeds of 111-135 mph.

But Castellini does have experience studying storms: She spent time with a storm-chasing team while developing the exhibit before its 2010 opening. (Castellini also was featured earlier this month on the CBS weekend show “Mission Unstoppable” for her contributions to the Hyde Park museum.) She spoke with the Tribune early Monday.

Five things to know about tornadoes:

1. Tornadoes come from supercell thunderstorms, she said “which are the strongest kinds of thunderstorms there are.” A tornado’s power depends on the power of the storm. Meteorologists think late Sunday’s was at least an EF-2 tornado — a ranking on the Enhanced Fujita scale, which goes from 0 to 5. An EF-2 would mean the tornado had wind speeds of 111-135 mph. EF-5 means wind speeds of about 300 mph. (The scale was devised in 1971, in part by Ted Fujita of the University of Chicago, and is a measure of both wind speed and damage caused by the tornado on the ground.)

2. The spinning funnel cloud comes from air movement up and down. When warm, humid air and cool, dry air combine in a storm, the warm air rises and the cool air falls. “Air moves just like a fluid,” said Castellini, if you can picture that. “So as these air masses move, you’re going to get some winds; they’re fighting for position in the atmosphere.” Vertical movement is conducive to creating a spin. The spring creates the tornado’s funnel cloud.

3. Tornadoes form most easily in wide-open areas, like farm fields. They’re sensitive to disruptions from the ground, which makes them forming in a dense suburban area, such as Naperville, less likely, and in a city like Chicago less likely still. Sunday’s tornado may have formed in the open areas further out. They dissipate when they lose their energy, such as from less difference in air temperature or from expending too much energy amid obstacles on the ground.

4. Tornado Alley, where such storms are the most common, is the stretch of land from West Texas up through the Midwest into North Dakota, according to online magazine Live Science. That’s where the cooler air from Canada meets the tropical air from the Gulf of Mexico. Such regions are rare, Castellini said. There’s a similar region in China, “but you don’t have Tornado Alleys all over the world.”

5. Tornadoes are very localized. The phenomenon of a tornado leveling one building and leaving another across the street untouched is not just in the movies. “It can be the difference of a football field away,” she said. “But that being said, I would not suggest standing a football field away.” Damage is caused by both wind speed and air pressure differences, but the adage of leaving windows open in an attempt to equalize pressure probably won’t help much. “If the tornado is that close, you have bigger problems than air pressure.”

Science Storms, which teaches more about tornadoes, is included with admission at the Museum of Science and Industry Chicago, 57th St. and Lake Shore Drive; msichicago.org


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