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Have you ever wondered how meteorologists find out how fast the wind is blowing? They use a device called an anemometer. When you first see one, you might wonder how it could possibly measure the speed of the wind. It is simple and you can make an anemometer of your own and learn how to measure wind speed.
Though the anemometers used by weathermen are expensive and complicated looking, you can make one that works without spending much money. All you need are a few materials that are easy and cheap to get.
Materials you will need:
A hole punch
Five paper cups (size depends on how big you want your anemometer)
Duct tape
Scissors
Three wood dowels about a quarter inch thick
An empty water or soda bottle (20 oz. if you use small bathroom size cups, a liter if you are using larger cups)
A stopwatch
Assembling your anemometer:
In four of the cups, punch a hole in the side just below the rim or halfway down the cup.
In the fifth cup, punch four holes around the cup at the rim. This cup is the anemometer’s center.
Slide a dowel through two of the holes of the center cup and then slide another dowel through the other two holes so they cross in the middle of the cup.
Poke a hole in the bottom of the center cup using the third dowel and push it up so it is against the point where the first two dowels cross. Tape it securely at this point. This dowel is what will rotate as the wind blows.
On the ends of the dowels that cross in the center cup, attach a cup to each by putting the dowel end through the hole and tape it securely in place. The cups all need to face the same direction.
Place the center dowel in the water bottle so the cups are above the bottle. Now you are ready to calibrate and test your anemometer.
How to get your anemometer calibrated:
Get a parent or other adult to drive around the block at ten miles per hour on a day with no wind.
As you hold your anemometer out the window in the same position it would be if it were sitting on the ground, count the number of times the cups rotate on their axis during a thirty second period.
The number of times the cups rotate in thirty seconds while in a car moving ten miles per hour is the same number of times as would be the case in a ten mile an hour wind.
The reason you need to calibrate your anemometer this way is so you have a baseline to calculate wind speed. If at ten miles an hour, the cups spin ten times, you know that when the cups spin ten times in the wind, it means the wind is blowing at ten miles per hour. If you want to be as accurate as possible, do the same process at different speeds and record the results. For example, do the test to calibrate at ten, twenty and thirty miles per hour. This makes measuring wind speed easier and more accurate.
Now you know how to find out on your own how fast the wind is without needing a weatherman to tell you.
… and for those who just need one right now, this should help:
