Try This at Home: Miniature Clouds
Illustrated Concepts
When a gas is chilled below its evaporation point, it becomes a liquid.
What You Need
- 1 clear plastic 2-liter bottle with cap, rinsed and labels removed
- Matches
- Water
What To Do
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Make sure you have an adult with you to supervise this experiment.
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Put an inch of hot tap water into the bottle. Screw the cap on and shake the bottle vigorously for 20 seconds, then remove the cap and pour out the excess water.
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Light a match and drop it into the bottle. Put the cap back on and shake the bottle briefly. Make sure the cap is screwed on tightly.
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Repeatedly squeeze the sides of the bottle hard for 10 seconds. Wait a moment, then squeeze and hold the bottle in for several seconds before quickly releasing it.
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Look inside the bottle to see if a cloud has formed.
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Continue to experiment with squeezing and releasing the bottle. You may even try opening the bottle to release the cloud.
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Clean up.
What's Happening
When liquid water is heated, some of the molecules on the surface of the water get enough energy to escape as a gas. When you compress the bottle, you warm its contents, and the bottle fills with water vapor. The water vapor cools quickly when the bottles expands, causing the vapor to condense into tiny drops of liquid water, which is what clouds and fog are made of. The smoke from the match provides particles for the water to stick to, helping the droplets to form.
Fun Fact
Nitrogen is responsible for blue and purple colors in an aurora; oxygen makes red and green auroras.