In the United States, every spring and summer brings tornadoes, one of the world’s most spectacular and least understood weather events. The U.S. gets more tornadoes than anyplace on earth, usually over 1,000 annually, largely in the south central states, with Texas, Oklahoma, and Kansas getting the most violent hits. But you may not know that every state, including Alaska and Hawaii, has experienced tornadoes, and that west central Florida has an especially high concentration of tornadoes, though Florida’s twisters are generally weaker and short lived.
In addition, tornadoes vary widely in size and strength. Most tornadoes are only a few hundred feet across, but some have been known to be over 2 miles wide. Most have wind speeds of less than 100 miles per hour, but Oklahoma City experienced a tornado in 1999 with wind speeds measured at 318 miles per hour, a world record. Most tornadoes are on the ground for just a few minutes before dissipating, while some are confirmed to have lasted for over an hour.
But the most significant thing we don’t know about tornadoes is exactly how they form. It’s not enough to talk about the convergence of warm moist air with cool air and dry air, because those conditions occur all the time in the central U.S., and many other places, without resulting in a tornado. And most thunderstorms, the incubator for all tornados, live their life without spawning anything close to a tornado.
Tornadoes are more commonly believed to be the product of particular smaller scale events that take place within a storm cell, but there is still disagreement about exactly what those events are. One of the problems, of course, is that it’s impossible to set up shop inside a tornado to take detailed measurements. Tornadoes occur sporadically, and instrumentation that can survive such violent conditions is not easily deployed.
Forecasters have had decades of experience dealing with tornadoes, improvements in radar now help researchers accurately track wind patterns, and computer modeling even allows a certain amount of experimentation, and yet it’s still impossible to predict the detailed formation of a tornado much in advance. The variables are simply too many, and are not well enough understood.
So, with every tornado season, people throughout much of the United States can do little but look up at the darkening skys and wonder.
In addition, tornadoes vary widely in size and strength. Most tornadoes are only a few hundred feet across, but some have been known to be over 2 miles wide. Most have wind speeds of less than 100 miles per hour, but Oklahoma City experienced a tornado in 1999 with wind speeds measured at 318 miles per hour, a world record. Most tornadoes are on the ground for just a few minutes before dissipating, while some are confirmed to have lasted for over an hour.
But the most significant thing we don’t know about tornadoes is exactly how they form. It’s not enough to talk about the convergence of warm moist air with cool air and dry air, because those conditions occur all the time in the central U.S., and many other places, without resulting in a tornado. And most thunderstorms, the incubator for all tornados, live their life without spawning anything close to a tornado.
Tornadoes are more commonly believed to be the product of particular smaller scale events that take place within a storm cell, but there is still disagreement about exactly what those events are. One of the problems, of course, is that it’s impossible to set up shop inside a tornado to take detailed measurements. Tornadoes occur sporadically, and instrumentation that can survive such violent conditions is not easily deployed.
Forecasters have had decades of experience dealing with tornadoes, improvements in radar now help researchers accurately track wind patterns, and computer modeling even allows a certain amount of experimentation, and yet it’s still impossible to predict the detailed formation of a tornado much in advance. The variables are simply too many, and are not well enough understood.
So, with every tornado season, people throughout much of the United States can do little but look up at the darkening skys and wonder.
For more information, visit www.AllyKnowsWeather.com.
(Photo shown is courtesy of the NOAA Photo Library, NOAA Central Library; OAR/ERL/National Severe Storms Laboratory - NSSL)
(Photo shown is courtesy of the NOAA Photo Library, NOAA Central Library; OAR/ERL/National Severe Storms Laboratory - NSSL)
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