Tornadoes can be nearly invisible, marked only by swirling debris at the base of the funnel. Some are composed almost entirely of windblown dust and still others are composed of several mini-funnels. On average, the United States experiences 100,000 thunderstorms each year. Approximately 1,000 tornadoes develop from these storms. Although tornadoes do occur throughout the world, the United States experiences the most intense and devastating tornadoes.
Tornadoes produce the most violent winds on earth.
Tornado winds can approach speeds as high as 300 miles per hour, travel distances over 100 miles and reach heights over 60,000 feet above ground. According to the National Weather Service , about 42 people are killed because of tornadoes each year.