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Tornadoes are among the most beautiful, dramatic and deadly natural phenomena to cut across the face of the earth. A rapidly moving funnel of air, tornadoes can appear out of nowhere to upturn a town or farm, livestock and cars, trees and people. This walloping tunnel suddenly and abruptly connects land and sky. Its speed can vary from 40 to more than 300 miles per hour. Tornadoes can be found all over the world, but are most common in the flat prairie lands of the United States. There are about 800 tornadoes a year in the US, with every one resulting in an average of two injuries. Every 10 tornadoes leads to a human fatality.

The only redeeming thing about tornadoes is that they last 10 minutes or so. Few last an hour. Many last a few minutes, others but seconds. Their sounds can be terrifying and range from the whirling of an enormous fan to the roar of a jet engine. What the tornado is stirring up also makes a difference. On water it may sound like a waterfall. Better not get near enough to find out.

What makes a tornado? For long meteorologists have suspected that the differences in temperature between warm and cold air fronts during a thunderstorm could cause a tornado to form; certainly the rotating center of a thunderstorm is usually involved. Still, it is not entirely clear why some such storms spawn tornadoes and others don’t. Other times great temperature differences between air fronts are not involved. Sometimes hurricanes spawn tornadoes, other times they don’t. Suffice it to say that there is much that scientists don’t know about these strange vortices from the sky.

We are not even sure if they are becoming more frequent because of global climate change. It may be that increased population settlement in the way of tornadoes, and increased reporting about tornadoes make their numbers appear to be on the increase. The historical record for tornadoes does not go back far enough to compare, and the criteria used then may be different criteria used today. Once again, it is hard to say. Hopefully superior science and measurement tools will answer this question once and for all in the coming years.

Many thanks to the National Oceanic & Atmospheric Administration (NOAA) for one of the images on this page.