Weather Academy: Tornado in a Bottle Experiment

MONROE, La. (KNOE) - Last week, we learned all about how tornadoes form, so this week, we will put that knowledge to the test by making our tornado in a bottle. This is a fun and simple experiment that clearly illustrates how a vortex forms.

What you’ll need:

• Two soda bottles
• Vortex tube connector (if you don’t want to buy a connector, you can use a washer and heavy-duty tape)
• Food coloring
• Water

Steps:

1. Take one of the two-liter bottles and fill it ¾ of the way full with water.
2. Add food coloring to the water.
3. Connect the two bottles using your vortex tube or a washer and heavy-duty tape.
4. Flip the bottles so that the bottle containing the water is on top.
5. Start to rotate the bottles. First, you will see bubbles form, and then your tornado!

The water doesn’t fall to the bottom bottle right away because two substances can’t take up the same space. The water is heavier (denser) and wants to be closer to the ground than the air. The vortex allows both the air and the water to trade places simultaneously. Similar to a tornado, when we move the bottle, the water moves in a circular motion, which is called the centripetal force. Centripetal force is an inward-facing force that pulls an object or liquid toward the center of its circular path. The twister created in your bottle is caused by the water spinning towards the center of the bottle. These “center-pulling” forces are created by a combination of air pressure, water pressure, and gravity. The air moving upward into the top bottle is acting like our updraft in a thunderstorm, and we can see that in the form of air bubbles that eventually become our tor ado. The air bubbles disrupt the horizontal spin, and then gravity forces the water down, creating our vortex in the bottle. But a real tornado in the atmosphere is caused by a combination of wind shear, changes in atmospheric pressure, and centrifugal force. The vortex connects the storm cloud to the earth’s surface to make a tornado.

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