Fog is a cloud that touches the ground or the surface of a body of water.

Make Fog in a Jar!

The purpose of this experiment is to observe fog formation.

Black paper

Gallon jar

Colored warm water


Gallon size bag of ice

1. Tape the black paper on the back of the jar, so you can't see through the jar.

2. Fill one third of the jar with colored warm water.

3. Light the match and hold it over the jar opening.

4. After a few seconds, drop the match into the jar and cover the top of the jar with the bag of ice.

5. Record your observations.

Can you see anything happening inside the jar?

You should see a little cloud form. Repeat the experiment until you do.

Why does the cloud form?

The warm water heats the layer of air that it touches. Some of the water evaporates into the air forming water vapor. The warm air containing water vapor rises, and then cools, as it comes in contact with the air cooled by the ice. When the water molecules cool, they slow down and stick together more readily. The particles of smoke act as nuclei for “bunches” of water molecules to collect on. This process is called condensation.

As the atmosphere (air) cools, water vapor suspended in the atmosphere condenses into water droplets around condensation nuclei (tiny particles of dust, ash, pollutants, and even sea salt).