Tornado in a Bottle

 

Objective:

The primary principle addressed is that of energy transfer. The time necessary for this activity ranges from 15 to 30 minutes. The grade level ranges from K through 16. Students will learn the forces that help cause tornadoes.

List of Materials:

  • Tornado Tube bottle connector (available at The Nature Company or various weather catalogs for a nominal price)
  • In place of the Tornado Tube, you could use the caps to the bottles with 3/8" holes drilled in each.
  • Secure the caps together with duct tape after Step 3 in the "Procedure" Subsection. You can also use some rubber hose and hose clamps.
  • Two plastic soda bottles (two liter, one liter, or 16 oz.) - Do not use glass.

Procedure:

First, fill one of the soda bottles 2/3rds full of water. Screw the Tornado Tube on to this bottle. Next, attach the other empty plastic soda bottle of the same size to the other end of the Tornado Tube. Rotate this assembly so that the full bottle is on top. Do not tilt it. While placing your hand securely on top of the full bottle, shake the upper bottle in a circular motion. The tornado action then results. You may wish to experiment with food color in the water.

Key Points:

Adults and kids alike are fascinated by the tremendous energy output of tornadoes. In the U.S., tornadoes are common in the summer months, with more than 800 reported annually nation-wide. In fact, three-fourths of all tornadoes reported world-wide are found in the U.S. The most damaging tornadoes have wind speeds of 250 mph or more and can have paths in excess of one mile wide and 50 miles long. Know the tornado safety rules, in case a tornado occurs near you!

1. Tornadoes and similar actions in fluids, such as those that occur when water pours through a small opening, are called vortexes.

2. When the "Tornado Tube" is attached to two discarded soda bottles and given a little swirl to start, a vortex action begins, and is most fascinating to watch. This action can be described as the manifestation or concentration of kinetic energy from the relative motion within the fluid.

3. The potential energy is in the direct proportion to the volume of the fluid, and will be converted to kinetic energy as it descends, pulled through the small opening by the force of gravity. Beginning with a small rotation near the opening, the rotation becomes more and more violent, due to the increased rotational velocity as the molecules come closer to the center. This main traits a "hole" in the liquid as it continues to pour through the opening.

4. In the atmosphere, thermals and wind shear combine to produce a vortex in the air that we call a tornado.

5. The direction of rotation may be either clockwise or counterclockwise depending on the direction of any small initial rotation. In seemingly perfectly still liquids, the Earth's rotational velocity tends to determine the direction. (Counterclockwise north of the equator, and clockwise south of the equator.)

Extensions:

Students could design their own experiments to try to increase or decrease the violence of the vortex in the tube. For example:

  • hot vs. cold water
  • increasing or decreasing the pressure in the bottles (squeezing the bottles)
  • changing the amount of water
  • changing the liquid in the bottle

 

References:

http://www.onesky.umich.edu/kgs/htdocs/tornado_bottle.html

Tornado Tube, Division of Burnham Associated, 26 Dearborn St., Salem, MA 01970.
(617) 745-1788

Tornadoes: Nature's Most Violent Storms. U.S. Dept. of Commerce-NOAA, National Weather Service and the American Red Cross, Sept. 1992.

Keen, Richard A., 1987. Skywatch: The Western Weather Guide. Golden: Fulcrum. Inc.


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