How are clouds formed?

Materials Needed:

-1 Clear plastic 2-liter soda bottle (remove label)
-1 Sheet black construction paper
-Water
-Matches (Be sure to have adult supervision)

Instructions:

Step 1: Pour 2 inches of very hot tap water into the 2-liter bottle.

Step 2: Place your mouth over the opening and blow into it to ensure the bottle is fully expanded. Immediately seal the bottle tightly.

Step 3: Shake the bottle vigorously for one minute. This will distribute water molecules in the air.

Step 5: With adult supervision, light a match. Let it burn for two seconds, then drop it into the bottle. Quickly recap the bottle.

Step 6: Lay the bottle on its side with the black paper behind it. Press hard on the bottle for ten seconds. The bottle is strong, so don't be afraid to really push hard. Release, observe, and repeat until a cloud forms.

Step 7: When the cloud has formed, quickly unscrew the cap. You should see the cloud escape from the bottle. If not, give the bottle a light squeeze.

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Scientific Principle:

By following the steps, you have created the conditions necessary for cloud formation: water vapor in the air, smoke particles for water to collect on, and cooling of the air by lowering the air pressure within the bottle. Voila! Instant cloud formation. Clouds form when condensation collects dust particles, which you provided with the smoke from the match.