I grew up in St. Louis, and was no stranger to tornados. To me they had mystical powers, knocking a roof off of one house, leaving another house unscathed, and a third ripped all apart. Whenever it would rain my eyes would be up in the clouds, waiting for one to spiral out and touch ground. I never saw an actual tornado, or even heard one, although I did see a lot of dust devils and a waterspout once. I had a healthy fear of tornados, and luckily, in St. Louis, houses have basements so there is somewhere comfortable to go.
See how a tornado forms and breaks apart at the Tornado exhibit
The tornado vortex is one of many types of vortices that occur in our atmosphere. Hurricanes, frontal rainstorms, waterspouts, and “dust devils” are other examples of atmospheric vortices. Air vortices occur in the air around you all the time, revealing themselves only when they capture something you can see. For instance, when you see leaves whirling around on a sidewalk, an air vortex is present.
I never knew the science behind the tornado. What I did know I learned from movies like The Wizard of Oz, Twister, and the local weatherman. At one of the more popular exhibits purchased by the Arkansas Discovery Network for the Good Vibrations collection, you can learn about how the tornado cloud forms and see a mini-twister for yourself.
At the Tornado exhibit, a large mist generator, fans and a carefully-shaped structure produce the tornado you see. Random air currents cause both the creation of the tornado and its temporary cessation. This “tornado” is chaotic and unpredictable much of the time; wandering off the source of the mist, slipping out of the grasp of the shearing winds and presenting a delightful and ever-changing image. The four vertical aluminum tubes lining the sides have holes blowing air. You can blow at the tornado or pass your hand through it, and notice what it does; sometimes it takes a while for the tornado to form again.
Questions for thought (answer them in the comments section and share your knowledge!):
- What causes tornadoes to form?
- Which direction do tornadoes in the Northern Hemisphere spin? Do they all travel in the same direction once on the ground?
- Does the eye of the tornado have a high pressure or a low pressure? Why?
- What wind speed is considered a tornado? What is the scale used to rate the strength of a tornado?
Here’s your chance to make your own “Tornado in a Bottle.”
- Two 2-liter soda bottles
- A Tornado Tube™ plastic connector (available from science museums, science stores, novelty stores, and some scientific supply companies). Or, make your own using a washer with a 3/8 inch (9.5 mm) hole and electrical tape
- Optional: Small dropper bottle of food coloring and/or bits of paper
Make your own "Tornado in a Bottle"
Fill one of the soda bottles about two-thirds full of water. Add a little food coloring or paper bits to the water. Screw the bottles onto both ends of the plastic connector. (CAUTION: Do not screw the connector on too tightly!) Or you can tape the bottles together with the washer between them.
Place the bottles on a table with the filled bottle on top. Watch the water slowly drip down into the lower bottle as air bubbles up into the top. Rapidly rotate the bottles in a circle a few times and stop. Observe the formation of a funnel-shaped vortex as the bottle drains. Also, notice the flow of the water as it empties into the lower bottle.
You can make the vortex with a single bottle by twirling the bottle and holding it over a water basin or the ground to drain, but you lose the water and have to refill the bottle each time you use it.
What happens when you pull the drain after taking a bath? Which direction does the water flow down the drain? What other natural vortices have you seen?
For more details on this activity, go to www.exploratorium.edu/snacks/vortex/
Go to www.fema.gov/kids/tornado.htm for more info on tornados and how to stay safe.
The tornado exhibit is currently at the Museum of Discovery for a few more weeks, before it travels to Mid-America Science Museum for an indefinite stay.
Watch this video footage from FEMA kids: