Used in weather stations, anemometers are devices that measure wind speed. The anemometers used by meteorologists are quite expensive, but making your own isn't difficult to do. Whether your child has a school meteorology project or she's just interested in the weather, building a homemade anemometer is a fun project you and your child can do together using inexpensive materials you probably have around the house.
Hold the sticks of balsa wood in the shape of a cross and glue them together.
Once the glue is dry, press the nail through the centre of the cross to make a hole. Set the nail aside to use later.
Making sure the cups are all facing the same direction, glue the ends of the sticks to the bottoms of the cups. The cups should be on their sides, parallel to the ground so they can catch the wind.
Put one bead on the nail, then thread the cross onto the nail through the hole in the centre you made earlier. Put the remaining two beads on the nail.
Hammer the nail into the top of the wooden post.
Find a soft patch of ground in a place the wind can reach from all directions, then push the post into the ground.
Watch the wind cause the anemometer to turn. Count the spins by counting the number of times the coloured cup passes in one minute (use the stopwatch to time the minute).
This anemometer will give an approximate reading of wind speed. Note that 10 turns per minute equals about 1 mile per hour. For a more accurate reading of wind speed, repeat Step 7 four times and calculate the average number of spins per minute.
This anemometer may come apart in very strong wind.