Physics

Tornadoes are one of nature’s most violent types of storms. Every year in the United States, tornadoes cause widespread destruction and are responsible for hundreds of deaths and billions of dollars of damage. Also known as cyclones or twisters, these storms have a rotating, cyclonic shape. They appear in many shapes, colors, and sizes and can vary in strength, depending on the atmospheric conditions in which they form.

The formation of a tornado is generally associated with a large thunderstorm, known as a supercell. This type of thunderstorm has a very strong updraft, which causes an air mass to rotate violently and can give rise to hailstones. A supercell is capable of producing strong tornadoes with winds that can sometimes exceed 300 miles per hour (mph) (483 kilometers per hour [kph]). When tornadoes touch down, they can leave a path of destruction that stretches for miles. Winds from tornadoes can be strong enough to flatten buildings, uproot trees, and carry automobiles for hundreds of yards. The wind speed associated with a tornado is used to classify its intensity on the Fujita scale, which ranges from 0 to 5. On the Fujita scale, an F0 tornado has winds that range from 40 to 72 mph (64 to 116 kph), and an F5 tornado has winds that range from 261 to 318 mph (420 to 512 kph). In this experiment, you will create a tornado chamber and observe the characteristics of a tornado.

• 2-liter bottles
• washer
• tape
• water
• food coloring
• glitter
• data table

1. Fill the bottle two-thirds full of water. Add a few drops of food coloring and some glitter (this will represent debris and will make your tornado easier to see).
2. Place the 1-in. washer over the top of the bottle that is filled with water.
3. Take the empty, inverted bottle and place it on top of the filled one.
4. Tape the two bottles together securely.
5. With a click, turn the chamber upside down so that the filled bottle is on top.
6. With a click, swirl the bottle several times in a circular motion.
7. Observe your tornado. Repeat as many times as desired. Record your observations in your data table.

1. Sketch what your tornado looked like.
2. Describe the motion of the tornado you created. What happened when all of the water emptied out of the upper bottle?
3. Why was it necessary to swirl the bottles to create a tornado? What would happen if the bottles were not swirled?
4. What forces were acting on the tornado to make it rotate in the manner that it did?
5. How is your bottle tornado similar to a real tornado in nature? How is it different?
6. Why are the winds associated with a tornado more damaging than wind gusts moving in only one direction?

1. Students sketches will vary.
2. Students created a spiraling motion in the upper bottle that stretched down to the lower bottle. The “tornado” generally spirals and twists from side to side as the water empties out of the top bottle. When there is no water left in the top bottle, the tornado stops.
3. Swirling the bottles creates a spiraling vortex, much like the one created within a supercell by the merging of two different fronts. Without the spiral movement, water will just pass from the top bottle to the bottom one.
4. the spiraling force, created when the bottles were rotated, and the downward pull created when the water flows into the bottom bottle by the force of gravity
5. Answers will vary, but may include the following: The bottle tornado is similar in shape, rotation, and movement to a real tornado. Both tornadoes have a downward pull as well as a rotating force. However, the bottle tornado is contained in water, not air, and it does not cause widespread damage or move in a lateral direction.
6. Tornadoes have spiraling winds that create an upward draft surrounding a column of cool air being forced downward. Because of the variation in wind speed and direction, things tend to be whipped around quite a bit more than if a gust of wind blew in from one direction. Additionally, the rotation tends to pick up debris (as small as dust or as large as vehicles, rooftops, and mobile homes) and carry it some distance. The impact of debris held in a storm can cause as much if not more damage than the winds alone.