Abstract

Objective

In this experiment you will investigate how the speed of the wind is measured by an anemometer.

Introduction

Weather is happening all around us every day. But isn't it nice to know the weather ahead of time? Suppose you have a soccer game this weekend, what is the chance of rain? When you watch the weather forecast on the local news, you are watching the results of weather data that has been gathered by a meteorologist, who will use the data to try and predict the weather.

Click here to watch a video clip from a CYBERCHASE episode related to this Project Idea. Presented by pbskidsgo.org.

A meteorologist measures weather patterns to predict the weather forecast ahead of time. To track changes in the weather, a meteorologist uses weather instruments at a weather station. There are many different weather instruments, each made to measure a different feature of the weather:

• a thermometer to measure temperature
• a barometer to measure air pressure
• a hygrometer to measure humidity
• a rain gauge to measure precipitation
• an anemometer to measure wind speed
• a wind vane to measure wind direction

Watch the CYBERCHASE episode, by PBS KIDS GO!, on the right and watch as the CyberSquad heads to the Northern Frontier to solve a mystery by measuring and comparing wind speeds! Then get ready to test winds yourself. In this experiment, you will make your own wind meter, or anemometer. An anemometer is useful because it rotates with the wind. To calculate the velocity at which your anemometer spins, you will determine the number of revolutions per minute (RPM). To test your anemometer, you will set a fan at different speeds and count the revolutions per minute of your home-made anemometer. How well will it work?

Terms, Concepts, and Questions to Start Background Research

To do this type of experiment you should know what the following terms mean. Have an adult help you search the internet, or take you to your local library to find out more!

• wind
• atmosphere
• speed
• direction
• anemometer

• How does an anemometer work?
• Will high speed winds increase or decrease the number of turns of an anemometer?
• How can the number of turns and length of time be used to calculate wind speed?

Bibliography

• UCAR, 2000. "Web Weather for Kids," The University Corporation for Atmospheric Research (UCAR) . [accessed September 29, 2006]
  http://eo.ucar.edu/webweather/
• Dorros, A., 1989. Feel the Wind, New York, NY: Harper Collins.
• Thirteen/WNET New York. (2009). CYBERCHASE: Weather Watchers: Blowin' in the Wind. Educational Broadcasting Corporation, New York. Retrieved April 29, 2009 from http://pbskids.org/cyberchase/weather/wind.html

At Weather Wiz Kids you can learn all about the forces that shape the weather:

• Wicker, C., 2006. "Weather Wiz Kids: Wind," Weatherwizkids.com [accessed September 29, 2006]
  http://www.weatherwizkids.com/wind1.htm

At the Miami Museum of Science you can find out how to make your own weather instruments:

• Miami Museum of Science, 2000. "Weather Tools," Miami Museum of Science. [accessed September 29, 2006]
  http://www.miamisci.org/hurricane/weathertools.html

Materials and Equipment

• 5 three ounce paper cups (Dixie Cups)
• 2 soda straws
• pin
• paper punch
• scissors
• stapler
• sharp pencil with an eraser
• ruler
• a fan with at least three different speeds (high, medium, and low)

Experimental Procedure

1. Take four of the paper cups and use the paper punch to punch one hole in the side of each cup, about a half inch below the rim.
2. Take one of the four cups and push a soda straw through the hole. Fold the end of the straw and staple it to the side of the cup across from the hole. Repeat this procedure for another one-hole cup and the second straw.
3. Take the fifth cup and punch four equally spaced holes in the side of the cup, about a quarter inch below the rim. Then punch a hole in the center of the bottom of the cup.
4. Slide one cup and straw assembly through two opposite holes in the cup with four holes. Push another one-hole cup onto the end of the straw just pushed through the four-hole cup.
5. Bend the straw and staple it to the one-hole cup, making certain that the cup faces the opposite direction from the first cup. Repeat this procedure using the other cup and straw assembly and the remaining one-hole cup.
6. Align the four cups so that their open ends face in the same direction either clockwise or counter-clockwise around the center cup.
7. Push the straight pin through the two straws where they intersect.
8. Push the eraser end of the pencil through the bottom hole in the center cup. Push the pin into the end of the pencil eraser as far as it will go.
9. Now your anemometer is ready for use! It should look like this:

10. Now set up the fan on one side of the room and mark a line with tape on the other side of the room from the fan, about 6–8 steps away.
11. Turn the fan on low speed and stand on the line across the room. Hold up your anemometer and count the number of turns your fan makes in a minute. Get someone to help you time the minute with a kitchen timer so that you can do the counting.
12. If you find that the anemometer is moving too fast for you to count then you will need to increase your distance and try the experiment again. Remember, all of your data needs to be collected from the same distance for each speed, as a control.
13. Repeat step 11 for the other speeds of the fan (medium and high), each time taking at least three different readings and averaging the results. You can calculate the average by adding the three readings together and dividing the answer by three. You should keep your data organized in a data table like this:

    Fan Speed	Wind Speed in Revolutions per Minute (rpm)
    	1st Reading	2nd Reading	3rd Reading	Average
    Low
    Medium
    High

14. Now you need to make a graph of your data so you can analyze your results. On the left side of the graph (y-axis) put a scale for your anemometer readings in revolutions per minute. On the bottom of the graph (x-axis), put a mark for each of the different fan speeds (low, medium, high). Then draw a bar for the average reading for each of the fan speeds.
15. How did your anemometer work? What happens to the number of turns of the anemometer in revolutions per minute as the wind speed increases?

Variations

• Try using your home-made anemometer to measure the wind speed outside. You can track the changes in wind speed over several days at your home. How often does the speed of the wind change where you live?
• You can also take your wind meter around town to find out if some parts of town are more windy than other parts of town. If you live near the ocean, is it windier at the beach or inland? If you live near the mountains or a tall hill, is it windier at the top or at the bottom?
• Try making other weather instruments to track weather patterns in your backyard. You can make a rain gauge to measure precipitation and a wind vane to measure wind direction. Track the weather over several days. How does your data compare to the local news forecast?
• For a more advanced project, you can calculate the actual velocity of the wind. Calculate the circumference (in meters) of the circle made by the rotating paper cups. Multiply your RPM value by the circumference of the circle, divide by 60, and you will have an approximation of the velocity of at which your anemometer spins (in meters per second). Your anemometer doesn't need to be pointed in the wind for use. You should be aware that some forces are being ignored including drag and friction for this elementary anemometer design, so the velocity at which your anemometer spins is not going to be exactly the same as the wind speed.

• For more science project ideas in this area of science, see Weather & Atmosphere Project Ideas.

Credits

Sara Agee, Ph.D., Science Buddies

Watch CYBERCHASE on PBS KIDS GO! Check local listings or visit www.pbskidsgo.org/cyberchase. CYBERCHASE is produced by THIRTEEN in association with WNET. All rights reserved. CYBERCHASE is a trademark of THIRTEEN. The PBS KIDS GO! logo is a registered mark of PBS and is used with permission.

Last edit date: 2012-02-07 06:22:00