MAKING AN ANEMOMETER

… a science project for levels 2-4

An anemometer is a device that tells you how fast the wind is blowing. The device you can build is a model of a wind speed indicator. A real one will be able to accurately measure how fast the wind is blowing. Yours will give you only approximation of how fast it's blowing. It can't give you an exact wind speed.

The energy in the moving wind can be used to generate electricity. But you have to know how fast the wind is blowing before you can harness wind power.

What You'll Need

Scissors
4 small paper cups (like drinking cups)
A marker pen (any color)
2 strips of stiff, corrugated cardboard -- the same length
Ruler
Stapler
Push pin
Sharpened pencil with rubber on the end
Modeling clay
A watch that shows seconds

What to Do

Cut off the rolled edges of the paper cups to make them lighter.

Color the outside of one cup with the marking pen.

Cross the cardboard strips so they make a plus (+) sign. Staple them together.

Take the ruler and pencil and draw lines from the outside corners of where the cardboard strips come together to the opposite corners. Where the pencil lines cross will be the exact middle of the cross.

Staple the cups to the ends of the cardboard strips; make sure the cups all face the same direction.

Push the pin through the center of the cardboard (where the pencil lines cross) and attach the cardboard cross with the cups on it to the eraser point of the pencil. Blow on the cups to make sure the cardboard spins around freely on the pin.

Place the modeling clay on a surface outside, such as a a porch railing, wooden fence rail, a wall or a rock. Stick the sharpened end of the pencil into the clay so it stands up straight.

Your anemometer is now ready for use!

Measuring Wind Speed

You may not be able to tell exactly what the wind speed will be in km per hour. But you can count how fast your anemometer turns to get an idea of how fast the wind is blowing.

Using your watch, count the number of times the colored cups spins around in one minute. You are measuring the wind speed in turns or revolutions per minute. Weather forecasters' anemometers convert the revolutions per minute into kilometers per hour. Keep a record of the wind speeds you're measuring for the next few days.

Measure the wind speed at different times of the day. Is it the same in the morning; the afternoon; the evening? Move your anemometer to another location. Is it windier in other places? Do trees or buildings block the wind?

Wind speed is important for wind energy. Wind turbines -- which are the machines that change the movement of the wind into electricity -- need a constant, average wind speed of about 14 miles per hour before the wind turbines can generate electricity. That's why wind farms, where there are a lot of wind turbines grouped together, are located in windy spots.

Make a Calibrated Anemometer

It is quite easy to build a wooden anemometer such as the illustration with a hinged wooden flap.

To calibrate this to a degree of accuracy, you will have to stand on the back of a utility truck and mark where the flap is in 5kph intervals (ask the driver to drive at a constant 10kph, 15kph 20kph etc.