Weather science: How to make a cloud in a jar (2 different methods!)

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Don’t you just love looking at clouds in the sky? I sure do!

But how do they get there?

A cloud is formed when water vapor condenses into water droplets that attach to particles (of dust, pollen, smoke, etc.) in the air. When billions of these water droplets join together, they form a cloud.

As part of our weather unit, we read several books about clouds. Then we decided to get into some hands-on science by making our own clouds in a jar. There are several methods for making a cloud in a jar. In this post I share two methods we tried and I explain how they work.

You’ll find more resources for learning about weather on Weather Unit Study page my Weather Activities Pinterest board. 

We tried two methods for making a cloud in a jar. Both methods involve making water vapor and then providing some sort of particle for the water vapor to condense on. In the first method, we used hairspray as the particle source and in the second method we used smoke from a match as the particle source.

The hairspray method formed a denser cloud that was easily visible and quite impressive to view. The match method was super cool because of how quickly the cloud formed and then disappeared as the air pressure in the jar changed.

How to make a cloud in a jar using hairspray

For this method, you will need the following materials:

• A jar with lid
• About 1/3 cup hot water
• Ice
• Hairspray (which I forgot to include in the picture below)

Start by pouring the hot water into the jar. Swirl it around a bit to warm up the sides of the jar.

Turn the lid upside down and place it on the top of the jar. Place several ice cubes onto the lid, and allow it to rest on the top of the jar for about 20 seconds.

Remove the lid, quickly spray a bit of hairspray into the jar, and then replace the lid with the ice still on top. Watch the cloud form.

When you see a good amount of condensation form, remove the lid and watch the “cloud” escape into the air.

How does it work?

When you add the warm water to the jar, some of it turns to water vapor. The water vapor rises to the top of the jar where it comes into contact with cold air, thanks to the ice cubes on top. Water vapor condenses when it cools down. However, a cloud can only form if the water vapor has something to condense on to. In nature, water vapor may condense onto dust particles, air pollution, pollen, volcanic ash, etc. In the case of this activity, the water vapor condensed onto the hairspray.

How to make a cloud in a jar using a match

For this method, you will need the following materials:

• A jar
• A match
• A balloon with the bottom cut off (so you can get the balloon over the mouth of the jar)
• Warm water
• A flashlight

Pour enough warm water into your jar to cover the bottom 1/2″ of the jar.

Light a match, then hold the lit end in the jar for a few seconds to allow smoke to enter the jar. Then remove the match (or you can simply drop it into the jar – the flame will extinguish when the match hits the water).

Quickly cover the opening of the jar with the cut balloon.

With this next step, the goal is to change the air pressure in the jar by gently pushing and releasing the balloon. Be gentle as you do this to ensure that the balloon does not come off the top of the jar.

With your finger, gently push the balloon into the jar a little bit to increase the air pressure in the jar. Then release. As you release, you should notice a cloud instantly form inside the jar. You may want to shine a flashlight at the jar to help you see the cloud more clearly.

You can repeating the pushing and releasing several times and you will see additional clouds form.

How does it work?

When you add the warm water to the jar, some of it turns to water vapor. When you press on the balloon, you increase the air pressure in the jar, which results in warmer air. When you then release the balloon, you decrease the air pressure in the jar, which results in cooler air. As the air cools, the water vapor in the jar condenses. The condensed water vapor is able to collect on the smoke particles from the match, and thus you see a cloud form.

More weather resources

More weather posts from Gift of Curiosity:

• Books about the weather
• Weather 3-part cards
• Water cycle demonstration
• Cloud classification activities
• Cloud classification craft
• Make it rain in a jar
• Wind resistance experiment
• How do hurricanes form?
• Make a hurricane
• Printable weather Bingo game
• Printable weather Bingo game

You’ll find more resources for learning about weather on Weather Unit Study page my Weather Activities Pinterest board. 

Follow Katie @ Gift of Curiosity’s board Unit Ideas: Weather on Pinterest.