Clouds in a Jar

When air is compressed the temperature goes up. Warm air holds more moisture than cool air. When air expands it becomes cooler. Droplets are formed and a cloud appears.

What you need:

What you do:

Drill a hole in the center of a cork which fits snugly into the mouth of a large glass jar. Insert a glass tube into the hole in the cork. Rinse the inside of the jar with water mixed with a small amount of alcohol. Pour out the water, leaving the inside of the jar wet. Add several pinches of finely crushed blackboard chalk. Put the cork and tube into the neck of the jar. Blow through the tube to scatter the chalk and compress the air, then suck very hard and suddenly on the tube. This will allow the air to expand. Did a cloud form?

Used with permission from Science Activities from A to Z
by Dr. Helen Challand and Elizabeth Brandt with illustrations by Herb Rudd.
Courtesy Digital Atlas of Idaho 2000.