Make a Cloud

There’s water vapor all around us. These simple experiments help explain how clouds form.

First, make some water vapor yourself! Put your hand in front of your mouth and breathe out quickly five times. Now touch your hand. What do you feel? Moisture! You can really see water vapor during cold weather when you breathe.

Now try the experiment below to make a cloud.

Here’s what you need:

  • Clear, empty glass
  • Freezer
  • Oven mitt

Here’s what to do:

  1. Put a dry, empty, clear glass into the freezer. Leave it in the freezer for 15 minutes.
  2. Remove the glass from the freezer with an oven mitt and breathe gently into the glass.
  3. Watch what happens.

What happened?

There’s a “cloud” inside the glass. The cloud formed when the water vapor in your warm breath came in contact with the cold glass surface. This is similar to how clouds form in the sky. Remember, temperatures at higher altitudes can be considerably below zero even when it’s warm on the ground. In the sky, the extra air condenses to form clouds. Water vapor inside the clouds will eventually condense and the water will fall back to the ground as rain, snow or hail.