We woke up one spring morning to hail coming down hard. Once the storm passed, the kids filled their sand buckets with hail, and the questions started. Where does rain come from? How do clouds form?
That was the perfect time for a cloud in a cup. This easy condensation experiment makes a real little cloud inside a jar, and you can let it float out when you lift the lid.
How to Make a Cloud in a Cup
Weather Geoboard Task Cards
Get the printableClear glass jar or cup
Very hot water
Ice
Small bowl or plate to cover the jar
Aerosol spray, like hairspray or air freshener
Warm the jar
Rinse the glass jar with warm water so it doesn’t crack when the hot water goes in.
Add hot water
An adult pours 1 to 2 inches of very hot water into the jar. Hot tap water wasn’t hot enough for us. We needed water heated to about 130°F.
Cover with ice
Set a small bowl or plate of ice on top of the jar.
Add a quick spray
Lift the ice bowl, give one quick spray into the middle of the jar, and put the bowl right back.
Watch the cloud form
A cloud swirls inside the jar within a few seconds.
Let it escape
Lift the bowl and watch the cloud float out. The cloud itself isn’t hot.
Safety note
A grown-up should heat and pour the water and handle the hot jar. Aerosol sprays are flammable, so keep them away from any flame and spray only a little. Don’t let kids breathe in the spray.
The Science Behind a Cloud in a Cup
Real clouds form the same way. Warm water evaporates into water vapor, and warm air rises. When it hits cold air, the vapor cools and condenses into tiny water droplets.
Those droplets need something to cling to, like dust or smoke in the sky. In the jar, the spray gives the droplets something to grab onto, and you get a cloud.
What we learned
Our first try didn’t work because the water wasn’t hot enough, which was a great lesson in itself. We tried sunblock spray first, and it turned the water a funky color. Plain hairspray or air freshener works much better.
While we waited, the kids explored the hail, comparing hot and cold side by side. Meatball even dropped a leaf in to see if it would melt too.
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Love easy science? Try our crawling colors experiment next.
Weather geoboards include
- Weather picture task cards
- Full mat geoboard activities
- Instant PDF download, nothing is shipped
Perfect for
- Weather units
- Spring science
- Preschool through 1st grade
- Fine motor centers
Cloud in a Cup FAQ
Hot water makes water vapor. The ice cools it, and the vapor condenses onto the spray particles, making a cloud.
Usually the water isn’t hot enough. Hot tap water often isn’t. Try water around 130°F.
Air freshener works too. You can also light and blow out a match over the jar for smoke, but that’s a grown-up only step.
No. By the time it floats out, it isn’t hot.
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From families like yours
Did you try it? Tell us how it went!
We love seeing these activities out in the wild: the lumpy letters, the snack breaks, the proud “I made a B!” moments. Leave a star rating, tell other parents what worked (and what totally didn’t), and add a photo of your setup if you’d like.
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