How to Measure the Wind Speed Using a Windsock

You can use a FAA compliant windsock to measure wind speed from 3 to 17 miles per hour.

A windsock is a kite made from a tube of cloth. One end of the tube is held open by a ring. The narrow end of the sock points in the direction of the wind. Windsocks help pilots figure out which way the wind is blowing as they come in to land. A windsock that meets Federal Aviation Authority (FAA) standards will extend fully when the wind reaches 17 miles per hour and will be limp at three miles per hour. You can use this knowledge to approximate wind speeds using a wind sock.

Instructions

1. Sketch a picture of a windsock on a day when it's fully extended. Make sure the sock doesn't have any bends or kinks in the picture. This is your baseline of 17 miles per hour. Check with your local weather service to make sure the wind speed is at least 17 miles per hour.

2. Draw a picture of your sock on a day when there is no wind.

3. Pick a day when the weatherman reports that the wind is blowing constantly at a certain speed (a light breeze of 3 miles per hour, for instance). Sketch the shape of your windsock.

4. Repeat Step 3 as many times as necessary to develop six or seven sketches of your windsock shape at certain speeds.

5. Make a chart from the data you have collected. The chart should have several pictures showing the shape of your sock and the reported wind speeds.

References

• NASA: Windsocks
• FAA: Windsocks
• Cape Wind: Measuring the Wind