Learning Lesson: Toasty Wind

Overview

The air is almost always in motion, and we feel this as wind. There are many sources for wind: mechanical sources such as fans and natural sources such as storms. But what is the actual cause of wind in the atmosphere? Using a toaster, the students will observe that wind is created by the heat that rises.

Procedure

1. Turn the toaster on to allow the unit to heat.
2. Ask the students where wind comes from.
3. Ask the students if a toaster can create wind.
4. Hold the pinwheel 10 to 15 inches (25 to 40 centimeters) above the top of the toaster to allow the pinwheel to spin.
5. Turn the toaster off.

Discussion

Most younger students will say clouds or trees cause the wind and that toasters cannot produce wind. They will quickly see that toasters do produce wind. Explain that wind is just air molecules in motion.

The glowing coils in the toaster produces infrared radiation, heating the air inside the toaster. Heat makes the air less dense than the surrounding air, and so it rises, creating wind.

The source for the Earth's heat is the Sun. The radiation from the Sun heats the ground, and the ground, in turn, heats the air. As demonstrated, the warm air rises – or more accurately, gravity pulls the cooler, denser air above and around it down, lifting the warm air up. This movement results in what what we feel as wind.

The faster the air rises, the faster the wind blows to take its place (or, again, more accurately, the faster the cooler/denser air sinks, the faster the wind blows away from the sinking spot). Every time will feel the wind, regardless of which direction it comes from, air is rising somewhere. The term for this rising warm air is convection, and it is responsible for the wind patterns we experience.