Hobbies And Interests
Cardboard Anemometer
Cut two strips of thin cardboard that are equal length, then measure and mark the center of each strip. Staple the strips together in the middle to form an X. Staple a small paper cup at the end of each strip, with each cup forming a T at the end of the strip. The cups all need to face the same direction, with the outsides all facing either clockwise or counterclockwise. Use a push pin to secure the middle of the cardboard X loosely to the end of a dowel rod; the cups must be on the underside of the X. The X needs to rotate freely. Push the anemometer into the ground, or create a base for it out of a material like modeling clay. Don't leave this anemometer out in the rain.
Easter Egg Anemometer
If you have plastic eggs left over from Easter, they can be used to make a more durable anemometer, but kids will need some help from an adult. Take two thin, equally sized strips of wood, mark their centers, then glue them together into an X shape. Use a small screw to attach half of a plastic Easter egg to the end of each wood strip, with the screws facing into the egg for safety. Use only tops or only bottoms. The eggs must all face the same direction, forming a T with the end of the wood strip. Use some glue for extra support if needed. Drill a hole in the center of the wood at the X, then use a nail to loosely attach it to a large dowel rod or other piece of wood. Be sure that the anemometer rotates freely.
Protractor Anemometer
Drill a small hole into the end of a plastic protractor along the baseline, then attach it to a dowel rod with a screw. Attach a very small tubular spirit level to the baseline of the protractor. It must align exactly for the anemometer to be accurate. Make a small hole in the middle of the baseline of the protractor, then attach a strong piece of fishing line with a few knots and some glue. Poke a hole through a ping-pong ball, and thread the fishing line through the ball. The length between the hole in the protractor and the top of the ball must be 30 centimeters, or 11.8 inches. Securely attach the fishing line to the ball using more knots and glue. Color the fishing line with nail polish, then remove any excess fishing line. The line will be at different angles according to the wind speed; to read it, hold the anemometer away from your body with the bubble in the level in the exact middle. This anemometer requires some help from an adult, but it doesn't require counting revolutions, which makes it easy to read.
Calibrating an Anemometer
A homemade anemometer can measure wind speed just like a profession anemometer can, but a homemade anemometer is not calibrated -- that is, you have no way of knowing how many revolutions the anemometer will make at a certain wind speed. One way to calibrate an anemometer is to compare it to one that is already calibrated. You can also drive slowly along an empty road with the anemometer and count the revolutions over a minute. If you were going 15 miles per hour, for example, the number of revolutions you counted would equal the number of revolutions you would see if the wind speed was 15 miles per hour. This method is a little dangerous and should only be done by an adult.