A fire tornado is just like a tornado but made of fire instead of air.
When we picture a tornado, most of us imagine a whirling column of air poking down from the clouds. But this tornado-like effect is not limited to just air. A fire tornado or fire whirl is just like a tornado but it's made of fire instead of air. As the heated air from the fire rises, strong air currents (often whipping through the trees) cause the air molecules to spin (often referred to as angular or rotational momentum) which shapes the flame into a tornado.
- Lazy Susan (rotating tray)
- Metal screen - the size will depend on the size of your Lazy Susan
- Wire or staples
- Glass or metal dish
- Pieces of sponge
- Lighter fluid
- Safety glasses
- Fire extinguisher
ADULT SUPERVISION REQUIRED! This demonstration write-up is provided for educational purposes only and should only be performed by properly trained science demonstrators.
- Roll the wire screen into a cylinder about the diameter of the Lazy Susan. Fasten the ends of the cylinder using wire or staples. Find a way to temporarily secure the screen to the Lazy Susan so that the screen does not fall over when the tray spins. You'll want to be able to quickly remove the screen in order to extinguish the fire.
- Place the glass or metal dish in the middle of the Lazy Susan (tray). It is best to find a small square of fire resistant material (a small plate or saucer) for the dish to sit on so as not to damage the Lazy Susan.
- Cut up several pieces of sponge and place them in the dish. Soak the pieces in lighter fluid.
- Put on your safety glasses. Light the fire but leave the mesh screen off of the Lazy Susan for now and gently spin the tray. Notice how the fire spins, but no tornado effect is created. Extinguish the fire by covering it with a small plate.
- Re-ignite the fire and place the wire screen cylinder on the Lazy Susan. Gently spin the tray and watch as the fire twists into the shape of a tornado. The fire tornado will rise as the tray spins faster and faster.
- Remove the screen cylinder from the tray and extinguish the fire.
How does it work?
As you might have guessed, the secret is the screen that rotates around the flame. The rotating screen gives the air molecules an initial spin (called angular momentum or rotational momentum). The rotating air molecules collide with the hot air rising from the fire and the flame twists into the shape of a tornado.
The rotating metal screen is a simple way to illustrate the way winds whip through the trees in the forest and collide with the warm updraft from the wildfire. These so-called fire tornadoes can measure 30-50 meters tall (100-200 feet). Some of the largest fire tornadoes have measured more than a kilometer in height. It's easy to see how the rising column of twisting fire can dance along the tree tops, causing the fire to spread easily.
Josh - March 16, 2011
It does work, I, a ninth grader, used it for science day and i hope to get a 100. But mine worked better with 96% rubbing alcohol. Less bad smelling bad lower heat and better tornado.