Cloud in a Bottle

Cloud in a Bottle

Where do clouds come from? How are they made? What are the made of? Check out this video of one of our favorite science demonstrations – the Cloud in a Bottle - and learn how to make your own using the instructions below!


  • 2-liter bottle 
  • Rubbing alcohol 
  • Bicycle pump with rubber stopper (cork works, too) 


  • Fill the 2-liter bottle with about half cup of rubbing alcohol 
  • Wait three minutes for the alcohol to evaporate a little 
  • Insert the rubber stopper into the top of the bottle and pump until you can hardly hold the stopper in the bottle top! 
  • Remove the stopper from the bottle to see what happens! 

What's going on?

What did you see happen when the rubber stopper was removed? What did you hear? 

You probably saw what looks like a cloud instantly form inside the bottle, and you probably heard a loud rush of air as well.  

Clouds form when individual gas molecules stick together to form tiny liquid droplets. These droplets usually form around some sort of particulate matter, like a small piece of dust. When huge groups of these liquid droplets come together and float, they form a cloud.  

The clouds in our sky are made of water, but the cloud in the bottle is made of alcohol. The reason we use alcohol is because it evaporates (or turns from liquid to vapor) much more quickly than water.  

When air is forced into the bottle using the bike pump, the pressure of the gas dramatically increases. As the gas molecules are forced closer together, the temperature increases as well, allowing the air to fit more vapor particles. Once air rushes out, the pressure and temperature dramatically decrease. This change in temperature and pressure forces the vapors to condense into liquid droplets, which creates a visible cloud.  

How long does it take for the cloud to disperse? What happens to the cloud when you insert the rubber stopper and pump more air back into the bottle? 

FUN FACT: While Earth’s clouds are made mostly of water, clouds on Jupiter are made of ammonia and methane! What else could clouds be made of?