You can measure how fast the wind is blowing using a few simple items. Building a wind speed indicator is easy and teaches enough about basic weather science to be used as a science project. Professional weather people call it an anemometer, which tells you how fast the wind is blowing. Your device only approximates the wind speed. However, with a little ingenuity and applied scientific methods, your device can closely measure the exact wind speed.
Cut off rolled edges on four paper cups. Colour the outside of one of the cups with a marking pen.
Lay cardboard strips or balsa to form a cross or plus (+) sign. Staple them together well.
Use a ruler and pencil and draw lines from the outside corners of where strips come together to corners opposite. The intersection of the drawn pencil lines is the centre of the crossed strips. Staple cups to strip ends, keeping all cups facing same direction.
Push the pushpin through the centre point at intersection of pencil lines. Attach crossed strip and cup assembly to eraser point of pencil.
Place brick of modelling clay on outside surface such as rail, table or rock. Push the sharpened pencil into the modelling clay in an upright position.
With a stopwatch, count the number of times the marked cup spins during a one-minute cycle. You are recording the wind speed in revolutions per minute (rpm) or the number of turns per minute. Professional weather forecasters have anemometers that convert revolutions per minute into miles per hour or kilometres per hour.
Your wind speed indicator can be calibrated as a group project, using one person to drive a car and another to hold the device out the window. One person holds a stopwatch and counts revolutions per minute on the wind speed device. Drive exactly 10mph. Record how many revolutions the wind speed indicator makes. Assuming there was no external wind, the number of revolutions made by your wind speed indicator equals 10mph.
Verify the accuracy of your measurements by employing a real anemometer similar to the ones used at airports and weather forecasters.
Measure wind speed at different times of day. Try morning, noon and evening and note if they are the same. Try moving your wind speed indicator to different locations and note differences.
Do not operate outside in inclement weather. Adults should be used to help you calibrate your wind speed indicator with a car.