What's in the Wind? Windy Day Experiments
- Monday, April 27, 2009
In J.R.R. Tolkien’s The Hobbit, this riddle is asked:
Voiceless it cries,
Do you know the answer? It is the wind.
If you think about it, you have not seen the wind. You have seen the items the wind moves. You may have felt the sharp, cold pressure of the wind on your face. You may have even seen large objects such as trees or buildings knocked down by the wind. Although you have not seen the wind itself, you know that it exists.
What causes the wind?
The wind blows because the sun heats up the earth. However, the sun does not heat every area of the earth equally. This causes an uneven temperature around the planet. The air heated by the sun near the equator rises and floats toward the cold areas of the poles. After this occurs, the cold air has room to move in and replace the air at the equator. As the air moves around the earth, it creates wind. The movement of the earth also contributes to the wind’s movement. The wind actually helps spread heat around the earth. So God has a use for the wind! This is a very simple explanation—there’s a lot more that can be learned. We will try three wind experiments to help us investigate the wind in our areas of the world.
Experiment #1: Anemometer
Our first experiment is going to measure how fast the wind is going in your area by making an anemometer. Meteorologists use anemometers to measure wind speed. Yours will not be as accurate as the professionals’, but it will give you a good idea of how fast the wind is moving outside your window.
- Four small paper cups (like paper drinking cups)
- A marking pen (any color)
- Two strips of stiff, corrugated cardboard, both the same length
- Flat push pin or small nail
- Sharpened pencil with eraser on the end
- Modeling clay
- Watch that shows seconds
First, cut off the rolled edges of the paper cups to make them lighter. Then decorate the outside of one cup with the marking pen.
Next, cross the cardboard strips so they look like a plus (+) sign, and staple them together. With the ruler and pencil, draw lines to form an x on the overlapping areas of the cardboard. Where the pencil lines intersect to form the x will be the exact middle of the cross. (You will use this point later.)
Staple the cups to the ends of the cardboard strips; make sure that all of the cups face the same direction.
Push the pin through the center of the cardboard (where the pencil lines cross) and attach the cardboard cross with the cups to the eraser point of the pencil. Blow on the cups to make sure the cardboard spins around freely on the pin.
Place the modeling clay on a surface outside, such as a porch railing, wooden fence rail, a wall, or a rock. Stick the sharpened end of the pencil into the clay so that it stands up straight. Make sure that it is secure and will not fall over if it is blown on.
Using your watch, count how many times the colored cup spins around to your side in one minute. If you measure this at different times, you will find that there are different wind speeds.
Experiment #2: What is in the Wind?
As we discussed earlier, the wind can carry items. Sometimes we do not even see the items it is carrying. In this experiment, we are going to try and capture the small items carried by the wind.
- Plastic lids
- Petroleum jelly
- Magnifying glass
- Paper hole punch
- Yarn or string
- Windy day
First, punch a hole at one end of each lid. Then, thread each hole with a length of yarn and knot the ends of the yarn together to form a loop like a necklace for hanging.
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