Cloud Maker

In science class, you have been exploring features of Earth's atmosphere. Clouds form when water vapor condenses in air. You can see it happen by doing this activity.


A jar half filled with water with a plastic bag attached to the rim.


Pour about a cup of warm water into the wide-mouth jar. Have an adult hold a lit candle in the jar. Then have the adult blow out the candle and keep it inside the jar for 5–10 seconds. Have the adult remove the candle and fit a plastic bag inside the jar, as shown. The open end of the bag should be wrapped around the outside of the jar. Secure the bag to the jar with the rubber band. Then have the adult hold the jar firmly against a table or countertop. Reach into the bag, take hold of the bottom of the bag, and quickly pull up, bringing the bottom of the bag outside the jar.


What do you see inside the bag? What happened to the air trapped inside the jar? What happened to the water vapor in the jar when it cooled? What happened to the particles of smoke?