What Is a Tornado?
Twisters, cyclones, waterspouts, whatever you might know them as – tornadoes are the Earth’s most violent storms. Here is a definition of tornadoes plus links to Web sites to learn more.
What is a tornado?
A tornado is a violent windstorm characterized by a twisting, funnel-shaped cloud. It is spawned by a thunderstorm (or sometimes as a result of a hurricane) and produced when cool air overrides a layer of warm air, forcing the warm air to rise rapidly.
The damage from a tornado is a result of the high wind velocity and wind-blown debris.
Facts about tornadoes
- Tornadoes have been reported in every state. No areas are immune to tornadoes.
- Approximately 1,000 tornadoes occur in the United States each year, more than in any other country in the world.
- Tornado season is generally March through August, although tornadoes can occur at any time of year.
- They tend to occur in the afternoons and evenings: over 80 percent of all tornadoes strike between noon and midnight.
- Tornadoes are classified on the Fujita scale with ratings between 0 and 5, F0 being the weakest and F5 being the strongest. See the NOAA Fujita Tornado Intensity Scale.
- On February 2, 2006, the National Oceanic & Atmosphere Administration premiered the Enhanced Fujita (EF) scale, which will go into effect in 2007. The original Fujita scale classified tornadoes based on damage to homes. The new EF scale classifies tornadoes by the Degree of Damage for different structures – mobile homes, offices, malls, etc. – as well as homes. Click here to learn more.
- The most violent tornadoes have rotating winds of 250 mph or more.
- When a tornado threatens, individuals need to have a safe place to go and time to get there. Even with advances in meteorology, warning times may be short or sometimes not possible.
- Preparation – knowing exactly what to do when severe weather strikes – can mean the difference between sparing life-saving minutes or drowning in chaos and confusion. See our Tornado – Get Prepared section.
For More Information
Ready.gov/Kids/Know the Facts – Launched in February 2003, Ready is a National public service campaign designed to educate and empower the American people to prepare for, respond to and mitigate emergencies, including natural and man-made disasters. The goal of the campaign is to promote preparedness through public involvement. Ready and its Spanish language version Listo ask individuals to do four key things: (1) stay informed about the different types of emergencies that could occur and their appropriate responses (2) make a family emergency plan and (3) build an emergency supply kit, and (4) get involved in your community by taking action to prepare for emergencies.
Lightning Safety – Check out the National Weather Service’s Lightning Safety site to learn more safety tips, stories, activities and facts about lightning. The National Weather Service (NWS) provides weather, hydrologic, and climate forecasts and warnings for the United States, its territories, adjacent waters and ocean areas.
National Lightning Safety Institute – Scroll to the bottom of the page and click on ‘Personal Lightning Safety’ or Structural Lightning Safety’. The National Lightning Safety Institute (NLSI) is a nonprofit, nonproduct advocacy of lightning safety for both people and structures.
NOAA Fujita Tornado Intensity Scale – A site explaining the Fujita Scale from F0-F5. The National Oceanic and Atmospheric Administration (NOAA) conducts research and gathers data about the global oceans, atmosphere, space and sun, and applies this knowledge to science and service that touch the lives of all Americans.
Protect Your Home From Hail Damage – Hail can do a lot of damage to a home. Read this article for preparedness tips. The Institute for Business & Home Safety (IBHS) is a nonprofit association that engages in communication, education, engineering and research.
Tornadoes – Questions and answers about tornadoes. The National Severe Storms Laboratory is a part of the NOAA. The National Oceanic and Atmospheric Administration (NOAA) conducts research and gathers data about the global oceans, atmosphere, space and sun, and applies this knowledge to science and service that touch the lives of all Americans.