How do tornaodes 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 updraft tilts the rotating air from horizontal to vertical.
  • An area of rotation, 2-6 miles wide, now extends through much of the storm.  Most strong and violent tornadoes from within this area of strong rotation.