Linda F. Malanson
(figure available in print form)
Wind is the movement of air caused by the uneven heating of the earth by the uneven heating of the earth by the sun. It does not have much substance—you cannot see it or hold it but you can feel its force. It can dry your clothes in summer and chill you to the bone in winter. It can be strong enough to carry sailing ships across the ocean and rip huge trees from the ground. It is the great equalizer of the atmosphere, transporting heat, moisture, pollutants, and dust great distances around the globe.
Air moves from area of high atmospheric pressure to areas of lower pressure. In an area of high pressure, the air molecules are closer together than they are in an area of lower pressure.
Air molecules tend to move from high to low pressure, and it is this movement of air that we feel as wind. The greater the difference between the two pressures, the stronger the wind will be. The earth’s rotation adds a curve to this flow from high to low pressure, creating a gentle spiral that twists inward.
EXPERIMENT: FLOWING WIND
(figure available in print form)
Air flows from a high-pressure area to a low pressure area, much as water flows from a higher to a lower level. This is demonstrated in this experiment. ADULT SUPERVISION IS NEEDED FOR THIS EXPERIMENT.
MATERIALS NEEDED:
1. scissors
2. food coloring
3. modeling clay
4. tape
5. 2 plastic bottles
6. a plastic tube
7. a hand drill and bit
8. water
DIRECTIONS:
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1. An adult drills a small hole near the bottom of each bottle (in the same position each time) and then cuts off the top of each bottle.
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2. The adult seals the bottle edges with tape. Stick strips of tape at equal intervals on both bottles to make a rough scale.
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3. Connect the two bottles by placing the ends of the plastic tube in the holes. Use some modeling clay to seal the joints.
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4. Fill one bottle with colored water to the level of the tube, and fill the other completely. What happens to the water levels?