|Earth Science:||Air Cells, Cyclone Formation|
|Grade Range:||Elementary School, Middle School, High School|
As a hands-on demonstration, students cannot actually handle it, but they can come up close to see the demonstration. For a stage demonstration you may need to use a larger glass or metal dish to hold the cotton balls.
- Cotton Balls
- Alcohol solution (70-80%)
- Metal Wire Cylinder
- Watch Glass or Small Fireproof Bowl
Please read the Fire section of the Demonstration Safety page before performing this demonstration.
This demonstration requires: goggles or safety glasses, fire-safe gloves. Have a fire extinguisher nearby, and keep a powdered fire retardant nearby.
- Presentation (Stage)
- Put 4-5 cotton balls into a small bowl, and set it in the center of the turntable. Soak the cotton balls with the alcohol solution.
- Show the setup to the audience and explain the scenario. Ignite the cotton balls, and ask the audience if they think anything might happen if you start spinning the plate. Spin the turntable to show that the bowl spins, but nothing special happens.
- Place the wire cylinder on the turntable around the bowl, and spin it again. This time, the audience will see a fire tornado form! Remove the cylinder and spin the turntable again to show that the effect is from the addition of it. Ask the audience for ideas on how the wire cylinder causes a fire tornado to form.
- When finished, smother the flame by placing a large watch glass or similar across the top of the bowl.
- Presentation (Hands-on)
- Put 2-3 cotton balls into a watch glass and set it in the center of the turntable. soak the cotton balls with the alcohol solution, and place the wire cylinder on the turntable around the watch glass.
- Show the setup to the students and ask them what they think might happen if you lit the cotton balls with the lighter, and started spinning the turntable. Proceed with the demonstration. They see a cyclone form!
- After every run with this demonstration, use a second watch glass to smother the cotton balls so the fire goes out. Reignite the cotton balls with every new group, and replace the cotton balls and solution as needed.
Why This Works
Cyclones largely differ from tornadoes because they do not require a strong storm system to form. Instead, a cyclone is what forms when air starts to spin and swirl on its own accord, due to things such as cross breezes, strong winds or quickly rising hot air. Most cyclones are pretty small, such as when you see sand spirals on the beach or swirling leaves in the fall, but if several factors are working together, then a cyclone can start to become dangerous. Fire tornadoes and dust devils are both types of cyclones, the former being made by a strong fire and a strong breeze, and the latter made by swirling air in a hot and dry climate.
When the turntable is spun without the wire cylinder, the bowl or plate merely spin slowly, and we see nothing form. This is because the air above and around it is not rotating, but standing still. The addition of the wire cylinder means that, when spun, the air within the cylinder becomes and air cell. An Air Cell is a pocket of air, within which we can note a difference from the rest of the air around, such as in water concentration or direction of movement. In this case, the air cell is influenced by the movement of the turn table because of the wire cylinder around it, and starts to spin. This spinning air, along with the rising air from the fire, will create a small cyclone.