The measurement of wind speed has evolved with technology. As early as 1805, Admiral Francis Beaufort created a wind scale based on observation. The Beaufort scale, still used today, measures wind effects on land and sea, from still air to hurricane-force winds. Wind socks show not only the speed, but the direction of the wind, as well. An anemometer, a multidirectional wind speed tool, gives the most accurate measure of speed. The wind turns the cups on a spindle, and a computer reads the number of revolutions per minute and calculates the wind speed.
- Skill level:
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Things you need
- Small paper cups, 5
- Hole punch
- Long drinking straws, 2
- Mini stapler
- Straight pin
- Pencil with an eraser
- Black marker
- Metric measuring tape
- Craft stick
Punch holes in four of the paper cups. Punch two holes in each cup, opposite each other, about halfway down the side of the cup.
Push a straw through both holes on one of the cups. Fold one end of the straw over and staple the straw to the side of the cup to hold it steady. Repeat with a second cup on the other straw.
Punch four holes, at equal intervals, halfway down the side of the last cup.
Slide a straw with a cup through opposite holes in the fifth cup. Position the cup in the straw so that the mouth of the cup is sideways. Place a cup on the other end of the straw. Make sure the mouths of the cups are facing in opposite directions. Fold the end of the straw over and staple to the side of the cup.
Slide the second straw through the remaining holes of the fifth cup. Turn the cup on the straw sideways so that the mouth of the cup faces the base of the cup in front of it. Attach the final cup on the other end of the straw. The mouth of the final cup will face the base of the cup in front of it. When finished, all four cups will be sideways with the mouth of each cup ready to catch the wind.
Arrange the straws so that the cups are equidistant from the centre cup. Poke the pin through the bottom of the cup and both crossed straws.
Colour the top of one of the cups black.
Push the pin into the eraser of the pencil. Test the device by holding the pencil near the point and blowing toward the cups. The cups should spin freely.
Measure the circumference of the cups in meters with a flexible measuring tape.
Take the new anemometer outside and stick the pencil into the ground. Stick the craft stick in the ground next to the device. Make sure that the craft stick doesn't touch the anemometer in any way.
Set the stopwatch for one minute.
Count the number of times the black cup spins over the craft stick in the minute.
Multiply the number of rotations per minute by the measurement of the circumference of the cups. The sum will be the speed of the wind in meters per minute.
Tips and warnings
- If the measuring tape is in inches, divide the measurement by 12 before multiplying the measurement by the number of rotations. This will give the speed of the wind in feet per minute.
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