Automotive

Let’s Actually Ask An Expert If Traffic Circles Could Make Tornadoes


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Photo: NCDOT

Thanks to the unknowable rules of the internet, a video clip from a Pennsylvania news program from a couple of years ago has re-surfaced, a clip that features an irate caller who blames the creation of tornadoes (or, in this case, tornaders) on traffic circles, which he claims are made when people driving around the circles create atmospheric disturbances that cause tornadoes. He is, of course, very wrong, very cranky, and perhaps a bit drunk, but I wanted to know more, so I reached out to a weather expert. Is there any chance such a thing could be possible?

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In case you haven’t actually seen or heard this clip, here you go:

So, yes, at first listen, this all sounds absurd. I’m pretty certain this is not remotely close to how tornadoes actually form. But I do know that it’s possible to synthesize artificial tornado-like systems using just directed air currents. In fact, to keep an automotive angle going, for some reason our pals at Mercedes-Benz have developed the world’s highest artificial tornado:

This tornado isn’t made with massive amounts of warm humid air colliding with cold, dry air. There are no thunderstorms happening, just jets of air in a big chamber. Is it possible that Mercedes-Benz is colluding with Big Traffic Circle to cripple our nation by creating massive tornadoes over every traffic circle and roundabout so that they can then swoop in and, um, profit, somehow?

I mean, probably. But I’m still not sure it’s possible to do it with traffic circles. What I want to know is if there’s any possible way at all to start a tornado-like effect with cars moving around a traffic circle—maybe the speeds would need to be significant, maybe the aerodynamic drag of the vehicles would need to be dramatic, like a chain of box trucks with parabolic dishes on their roofs driving constantly at 120 mph or something?

I asked weather writer Dennis Mersereau if there were any circumstances where this could work, and here’s what he told me:

Haha, no that’s a great question! I love it.

Cars would never be able to start a tornado. Tornadoes start with rotation up in a thunderstorm and stretch down toward the ground.

Now, you might be able to start a dust devil, which begins at the surface and stretches upward. Cars wouldn’t be able to start one by driving around in circles, though. Even with trucks, you wouldn’t get the focused spin needed to start that kind of small scale rotation.

If you were rich, had lots of free time on a hot, sunny day, and a heap of luck, you might be able to take a box truck or tractor trailer out to a desert or gravel field and drive really fast to try for a dust devil in its wake.

But I’m sad to say we have a better chance at teaching people how to negotiate a roundabout than generating a tornado with one.

Disappointed but undaunted, I showed him the Mercedes-Benz artificial tornado, and then asked about having vehicles with devices to really maximize their air displacement. His response:

Hey that’s cool! Never seen that one. Looks like they’re using blowers and a reversed fan in the ceiling. It’s more of a waterspout than a tornado. The wind in that demonstration can’t be more than a few mph. Open the door or try it outside and the spin would mix out in a flash and the demonstration would be a bust.

If you put sails or wings or any sort of Junkyard Wars/Mythbuster contraption on a truck to create wind, you might have a shot at spinning up a dust devil. But try it with lots of trucks and they’d have to drive in a tight circle and have a lot of luck to get one going. Even then, the wind from one truck would probably disrupt the wind from another and make it too turbulent.

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Image for article titled Let's Actually Ask An Expert If Traffic Circles Could Make Tornadoes

Illustration: Jason Torchinsky

So, as you likely guessed, no, of course not, this is idiotic. And, even with all my pushing and hypotheticals about crazy high-drag vehicles and trained drivers and ideal circumstances, at best all you can hope for is a big dust devil, which isn’t nothing, but it sure as hell isn’t a tornado.

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There. Now we’ve definitively settled something no rational human believed anyway. I may knock off early.

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