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How Do Tornadoes Form

Before thunderstorms develop, a change in wind direction and an increase in wind speed with increasing height creates an invisible, horizontal spinning effect in the lower atmosphere. Rising air within the thunderstorm's updraft tilts the rotating air from horizontal to vertical. Most strong and violent tornadoes from within this area of rotation.
How Do Tornadoes Form
Thunderstorm with rotation

Photo of thunderstorm, with rotation in the foreground, looking west. The Rotation is in the area of the lower cloud base. Spotters refer to this area as a rotating wall cloud. (Woodward, Oklahoma - Ron Przybylinski)

Tornado Touching the Ground

Moments later, a strong tornado develops within the area of rotation. Softball-size hail and damaging "straight-line" winds also accompanied this storm. (Woodward, Oklahoma - Ron Przybylinski)


'Tornadoes: Nature's Most Violent Storms' was developed by the National Oceanic and Atmospheric Administration (NOAA)/National Weather Service (NWS) in cooperation with the American Red Cross and the Federal Emergency Management Agency (FEMA). It is designed to assist in heightening public awareness and understanding the dangers associated with tornadoes. The package provides an introduction to tornadoes and their impact, discusses tornado development and occurrence, and describes safety information for homes, schools, places of work, and outdoors. In addition, basic environmental clues are presented.

Individual use of the pictures within these presentation must have prior approval from the credited source.
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