STEAM at Home: Cloud in a Jar

This week’s STEAM At Home project is weather science. We will be learning about how clouds are formed and make a cloud in a jar.


  • Jar with lid (mason jars work really well)
  • Ice
  • Hot Water
  • Pollutant (I used hairspray)

Heat up ⅓ cup of water. Poor the water into the jar, and swoosh it around the sides carefully so the glass heats up. Take the lid and turn it upside down, and fill it with ice cubes. Place the lid on top of the jar (still upside down so the ice cubes don’t fall into the jar). Wait 20 seconds. Remove the lid and add your pollutant, then put the lid back on top. Give your cloud another 30 seconds to form then remove the lid. Watch as your cloud escapes the jar and dissipates into the air.

What is happening?
The warm water turns into vapor in the jar and rises to the top. The ice lid creates cold air at the top of the jar. When the vapor reaches the cold air it starts to condense, but not enough to form a cloud. Clouds need particles to cling to in order to form. Examples of these particles are dust, pollution, smoke, ash, and pollen. I used hair spray which is a common pollutant. The water vapor in the jar clings to the hair spray while it is condensing, forming a cloud. You can sort of see it in the jar, but you can really get a clear view of your cloud when you release it from the jar.

Create your own cloud:
Now try to find ways of creating a cloud with other materials like dust or pollen. You can find examples of this online where people use matches, make sure you have your parents permissions if you want to try this though.Try changing the temperature of the hot water, make it warm to boiling. Is there a difference with the clouds. Try doing this in rooms with different temperatures, cold and hot. Does this affect the cloud when you release it from the jar?

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