Tornadoes and tornado deaths, sorted by Fujita class.
Click on image for full size
Courtesy of University of Chicago

Tornado Stats

Most of the world's tornadoes occur in the United States. The area where most of them develop is called Tornado Alley. About 750 tornadoes strike the U.S. each year and about 100 people are killed by these storms. Most only last a few minutes and travel only a few miles, but some can last much longer and travel over 100 miles.

Some really severe thunderstorms can spawn more than one tornado. These are know as tornado families. They can form one after another or they can form in a line. Some really strong tornadoes even break into smaller ones.

Tornadoes are divided into groups according to how strong their winds are. Violent tornadoes don't happen very often, but they cause the most destruction and loss of life. Meteorologists have new equipment and new knowledge that allows them to forecast tornadoes earlier. With an earlier forecast, they can issue warnings and tell the public to take shelter. This had helped lower the death toll due to tornadoes. But, scientists don't know how to stop tornadoes so they can't easily reduce the damage caused my them.
Last modified May 17, 2007 by Jennifer Bergman.

You might also be interested in:

Science, Evolution, and Creationism

How did life evolve on Earth? The answer to this question can help us understand our past and prepare for our future. Although evolution provides credible and reliable answers, polls show that many people turn away from science, seeking other explanations with which they are more comfortable....more

Tornado Forecasts

The short duration and complicated nature of tornadoes make them nearly impossible forecast. Meteorologists don't really know the specifics of how they form, but they do know what atmospheric conditions...more

Tornado Notification

Tornadoes are very destructive, so it's important to know when one may form so you can take shelter. Forecastors at the National Weather Service are always on the lookout for developing storms. Even though...more


Tornadoes form from severe thunderstorms. They have a very high energy density which means that they are very destructive to a small area. They also don't last very long which makes them hard to study....more

Wave Beats

Sound travels in waves. These waves have both a frequency and an amplitude. The frequency is measured in hertz, which is one wave cycle per second. A cycle is a repeated pattern of positive and negative...more

Chasing Tornadoes

Storms chasers are different than storm spotters. Chasers travel around Tornado Alley looking for severe storms and tornadoes. This area in the Great Plains is the best for chasing. Besides having a lot...more

Energy Density

A tornado is the most destructive force in nature; that doesn't mean it has the most energy. Thunderstorms which produce tornadoes can have 40,000 times as much energy as a tornado! Tornadoes are so destructive...more

The Doppler Effect

The Doppler effect was named after Christian Doppler, who first came up with the idea in 1842. He determined that the frequency of sound waves would change if either the source of the sound or the observer...more

Windows to the Universe, a project of the National Earth Science Teachers Association, is sponsored in part is sponsored in part through grants from federal agencies (NASA and NOAA), and partnerships with affiliated organizations, including the American Geophysical Union, the Howard Hughes Medical Institute, the Earth System Information Partnership, the American Meteorological Society, the National Center for Science Education, and TERC. The American Geophysical Union and the American Geosciences Institute are Windows to the Universe Founding Partners. NESTA welcomes new Institutional Affiliates in support of our ongoing programs, as well as collaborations on new projects. Contact NESTA for more information. NASA ESIP NCSE HHMI AGU AGI AMS NOAA