2C50.34 - Tornado Box - Vortex Stretching

Code Number:
Demo Title:
Tornado Box - Vortex Stretching
Turbulence and Vortex
Area of Study:
Heat & Fluids
Tornado box demonstration with rolling stand.

Start the ultrasonic vaporizer and allow some mist to accumulate in the bottom of the box.  Then start the fan and using a variac, set it to a speed that gives a good vortex.  Turn on the lights and adjust their intensity until the vortex is clearly visible.  Adjustment of the side inlets may also be needed to get the performance you desire.

Vortex stretching may be observed with this unit also.  Turn on everything except for the fan and allow a good layer of mist to accumulate in the bottom of the tornado box.  Turn on the fan and in a few second the layer of mist will start to swirl and a vortex will appear and stretch all the way up to the fan.  Adjust the side inlets on the box until you get the observation you desire. 

  • H. Richard Crane, "Doppler Radar: The Speed of the Air in a Tornado", TPT, Vol. 27, #3, Mar. 1989, p. 212.
  • Haym Kruglak, "Barometric Autograph of a Tornado", TPT, Vol. 19, #3, Mar. 1981, p. 182.
  • Perry L. Johnson, "The Squeezes, Stretches, and Whirls of Turbulence", Physics Today, Vol. 74, #4, April 2021, p. 46.
  • Paul Markowski, Yvette Richardson, "What We Know and Don't Know About Tornado Formation", Physics Today, Sept. 2014, p 26.
  • Kerry Emanuel, "Hurricanes: Tempests in a Greenhouse", Physics Today, Aug. 2006, p. 74.
  • "The Scientific Companion - Tornados", Popular Mechanics, May 2015, p. 60.
  • Theodore Gray, "Funnels of Flame", Popular Science, Apr. 2013, p. 72.
  • Corey Binns, "Twisted", Popular Science, Oct. 2010, p. 38.
  • Jearl Walker, "4.82, Firestorms", The Flying Circus of Physics Ed. 2, p. 213.
  • Jearl Walker, "2.39, Dust Devils, Fog Devils, and Steam Devils", The Flying Circus of Physics Ed. 2, p. 97.
  • Jearl Walker, "2.38, Waterspouts and Funnel Clouds", The Flying Circus of Physics Ed. 2, p. 97.
  • Jearl Walker, "2.37, Looking Up Into a Tornado", The Flying Circus of Physics Ed. 2, p. 97.
  • Jearl Walker, "2.36, Tornadoes", The Flying Circus of Physics Ed. 2, p. 96.
  • Steve Shropshire, Flame Tornado Demo, Idaho State University, Dept.of Physics, Box 8126, Pocatello, ID 83209.
  • William J. Beaty, "Tornado Generator Box", Science Fair Project, 1996.

Disclaimer: These demonstrations are provided only for illustrative use by persons affiliated with The University of Iowa and only under the direction of a trained instructor or physicist.  The University of Iowa is not responsible for demonstrations performed by those using their own equipment or who choose to use this reference material for their own purpose.  The demonstrations included here are within the public domain and can be found in materials contained in libraries, bookstores, and through electronic sources.  Performing all or any portion of any of these demonstrations, with or without revisions not depicted here entails inherent risks.  These risks include, without limitation, bodily injury (and possibly death), including risks to health that may be temporary or permanent and that may exacerbate a pre-existing medical condition; and property loss or damage.  Anyone performing any part of these demonstrations, even with revisions, knowingly and voluntarily assumes all risks associated with them.