Watch the wind blow by! Making, using, and understanding an ANEMOMETER OBJECTIVES:   1.  Construct and use an anemometer 2.  Investigate wind speed BACKGROUND INFORMATION:        An anemometer is an instrument that meteorologists use to measure wind speed.  One type of anemometer consists of four arms with cups on the ends that rotate freely.  Wind from any direction will catch one of the cups and start the rotation of the arms.  The faster the wind is blowing, the faster the arms will spin. To measure the wind speed, students will count the number of times the anemometer makes one complete rotation in 30 seconds.  They will multiply this number by 2, giving them the wind speed in rotations per minute (rpm).  Without a complicated calibration of the instrument they build, they will not be able to accurately convert their measurements to miles per hour.   PRE-LAB TEACHING STRATEGIES:      Make sure the students understand the purpose of an anemometer.  Initiate a discussion on the different things wind speed affects (helps or hurts) in the world. LAB NOTES:   1.   Any size wood pieces will work if you do not have a way to cut the strips to a particular size.  We recommend wooden rulers because they are a good size, they have a hold in the center, and they are inexpensive.  You may substitute any other materials you have available, just be sure that both spinning arms are the same length. 2.   One cup must be marked  “X” or painted so that the students can easily count the revolutions of the instrument. 3.   Answers to questions in observations: #2.  3 mph #3.  8 mph POST-LAB TEACHING STRATEGIES: Discuss   the   importance   of   making   accurate   measurements   in   predicting weather.   Discuss the fact that the wind in the upper atmosphere moves at a different speed than the wind on the surface of the earth.  Discuss some of the factors that might affect the speed of the wind.   Don’t forget to mention the differences in heating and cooling rates of various surfaces such as land and water, and how pressure gradients affect wind speed.   Details on all these subjects can be found by entering key words on google.com.