Imagine a very windy day, a day where it is hard to walk into the wind … and harder still to bicycle into it. In general, once a steady wind gets to about 30 mph, it will begin to impede your progress while walking.
But now put yourself in your living room, having returned home after walking into that wind. You settle down for a bite to eat, when all of a sudden, a particularly strong gust really rattles the house. You figure it had to be over 50 mph, so you walk over to your anemometer readout, push “high gust” and are surprised to see it was only 40 mph. The question is, why was it so window-rattling as compared to the 30 mph wind? After all, it’s only 10 mph stronger.
Well, the answer lies in the fact that when comparing the force exerted by the wind, you must first square the wind speed, that is, multiply it by itself. Let’s do it. 30 x 30 is 900. 40 x 40 is 1,600. Voila! We have our answer now. Even though that attention-getting gust was only 10 mph stronger, it exerted almost twice the force (77.7 percent to be exact).
So now take that attention-getting 40 mph wind gust and compare it to a violent tornado, such as the one which struck Greensburg, Kansas in May of 2007. That tornado had winds around 200 mph … so using that “squaring the speed” rule, the Greensburg tornado exerted 25 times the force of that attention-getting 40 mph example!
Now you can understand why, when a violent tornado moves through a populated area, everything is reduced to rubble.
Ted Shapiro holds the Broadcast Seal of Approval from both the American Meteorological Society and the National Weather Association. An Alexandria, Va. native, he has been Chief Meteorologist at WAGM-TV since 2006. Email him at tshapiro@wagmtv.com.
