Tornado (weather)
A tornado is the most intense form of windstorm found in nature. While there are variations, the most common presentation is a dark funnel-shaped cloud, most often moving from southwest to northeast in the Northern Hemisphere. Their internal winds can exceed 480 km/hr to 300 mph and their forward speed ranges from 0 to 110 km/hr-70 mph. [1]
They are most common over land, but can accompany hurricanes and tropical storms. A tornado that forms over water is called a waterspout. In the United States, they can occur anywhere, but are most common east of the Rocky Mountains in the spring and summer.
Since tornado formation can be detected by radar and other instruments, the best warning is weather radio. In high-risk areas, there may also be warning sirens, sounded either when there is a radio warning or a tornado is sighted. U.S. weather reporting uses two terms:
- Tornado watch: Tornadoes are possible
- Tornado warning: A tornado has been sighted visually or by radar
References
- ↑ Are You Ready? An In-Depth Guide to Citizen Preparedness, Federal Emergency Management Agency, August 2004, IS-44, pp. 58-64