Tornado in a bottle

Swirl water between two soda bottles, to make a whirlpool between them. Use as a weather model of tornados or space model of gas clouds swirling around a black hole.
Science content
Physics: Motion and Forces, Newton’s Laws, Gravity (K, 2, 6)
Lessons activity is in
  • two 2 litre soda bottles
  • water
  • optional: small foam pieces, beads or other small floating bits
  • ideally, a "tornado bottle connector" to connect the bottles end to end - I got mine from Scienceworld in Vancouver (also available online)
  • optional but ideal: washers to prevent small leaks - I use garden hose washers

If tornado connectors unavailable, the materials below:

  • drill and bit to remove the centres of the soda bottle caps
  • hot glue gun
  • duct tape

If no tornado connector is available:
Drill out the centre of the caps, then hot glue them together face to face, without sealing over the hole. More hot glue and duct tape will be needed to minimize leaks from the bottles during the activity. Have a towel ready.

Fill one of the bottles with water two thirds full.
Add the optional floating bits.
Add the tornado connector, or the home-made connector, before screwing on the other bottle.

Turn the bottles upside down so that the water is in the upper bottle, hold the bottles tightly at the join and rotate in a large circle to initiate a tornado of water down into the lower bottle. The floating bits will help visualize the rotation of the water through the tornado.

This activity can be used to model several real phenomena including:
1. Black hole accretion discs: the cloud of gas and dust swirling around a black hole form a spinning "accretion disc". Long streamers of gas are pulled into the black hole by gravity, travelling faster as they are pulled in. Although a black hole itself is not visible, the accretion disc around it is.
2. Tornadoes, hurricanes and waterspouts - although note that these swirl upwards not downwards.


Home made version leaks a lot! Add a towel to hold join with.

Grades taught
Gr K
Gr 1
Gr 6
Gr 7