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Tornado Model by Sullivan and Alexa

We're fascinated by tornados. Since studying real ones is dangerous, we decided to build our own tornado model to learn more about how these violent storms form. Our question: which is more important in forming a tornado, a sidewind or an updraft?

What did we do?
Our first attempt at making a tornado machine used an updraft fan only with a pan of steaming water to make the tornado visible. We weren't able to make a vortex this way so we revised our model to use two fans, one on the side and one for an updraft. We also added a cool mist humidifier make the tornado visible. We then set up a balsa wood model town so we could see how destructive the tornado was with each fan setting. The side fan had two settings, and the top fan had three.

What did we find out?
We found that with both fans on low speed we couldn't make a tornado vortex. Keeping the side fan on low made weak tornados. But once we increased the updraft fan to medium and high, we turned the side wind into a destructive tornado! So we concluded that the side wind is necessary but it doesn't become a destructive tornado unless there is a powerful updraft.

What can you do?
• Use a hair dryer (on the cool setting!) to create a small-scale wind. Make some small "trees" by sticking a toothpick into a marshmallow or gumdrop for the trunk and roots, and taping paper onto the toothpick to represent the leaves. Set up a whole bunch of trees, and investigate how far from the hair dryer the trees have to be before they aren't blown over by the wind. Think about why the wind strength seems to diminish the farther away you are from the source.

• Read about the F-Scale, and how it is used to estimate the wind speeds of real tornados.

• Use this weather investigation as a science fair project idea for your elementary or middle school science fair! Then tell us about it!

 SciLinks More on Wind Currents Go to the DFTV Boards, and tell us about your science investigation.

What country built the first windmills?