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How to Make Cloud Experiments

Clouds form when warm, moist air rises. As it rises, the air temperature gets cooler and eventually condenses to form tiny droplets of water. The water droplets are so tightly packed together that they become visible and make clouds. Air pressure also determines whether clouds can form. High air pressure means that the weight of air pushing downward is heavy. This makes it difficult for clouds to form, as the warm air can't rise enough to cool and condense. However, if the air pressure is low, then moisture can continue to rise until it condenses and forms a cloud. Cloud experiments can teach kid the basics of how and why weather systems form.

Things You'll Need

Small metal tray
Ice cubes
Glass
Clear plastic bottle (2- to 4-pint capacity)
Match

Instructions

Ice Cube Cloud
- 1
  Get about six or seven ice cubes from your freezer and put them on a small metal tray. Leave the ice cubes on the tray for about 5 minutes, so that the ice cubes make the tray cold. (You can also put the tray in the refrigerator for about 3 minutes, to speed up the cooling process.)
- 2
  Put about 1 inch of warm water into a glass. Move the glass from side to side to move the water about a bit. This makes water vapor rise from the warm water and speeds up the experiment.
- 3
  Place the tray on top of the glass containing the warm water. Look inside the glass and you will see a cloud forming near the top of the glass. This is because warm water vapor rises, but as the air at the top of the glass is cool, the water vapor condenses to form water droplets, which look like a cloud.
Air Pressure Cloud
- 4
  Pour 1 cup of warm water into an empty, clear plastic bottle. (A bottle that holds between 2 and 4 pints is fine.) Remove the cap from the bottle. Squeeze the bottle with your hand so that the air is pushed out of the bottle. Keep squeezing it.
- 5
  Light a match close to the neck of the bottle. Blow out the match and put the end of the match near the opening of the bottle. Immediately release the pressure your hand is putting on the bottle. Let the smoke from the blown-out match get sucked into the bottle and then replace the cap and tighten it. You will see the smoke swirling around inside the bottle.
- 6
  Squeeze the bottle. This increases the air pressure inside the bottle and the smoke will disappear. Stop squeezing the bottle and the bottle will fill up with smoke, replicating the look of a cloud.
- 7
  Repeat squeezing the bottle several times. Each time you squeeze, the smoke will disappear and then reappear once you release the pressure. When you squeeze the bottle, the increase in air pressure increases the temperature in the bottle so that the water and smoke molecules vaporize. Releasing the pressure means that the temperature drops and the vaporized water molecules condense and attach to the smoke molecules and are visible again, creating a cloud effect.

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