Tuesday, 18 February 2014

Cloud In A Bottle Science Experiment

With a few items you may already have around your home, you can make your very own cloud in a bottle. This is a nice easy home science project you can recreate yourself.

WARNING! If you attempt to make this yourself then take all necessary precautions and wear any necessary safety equipment. Be careful when handling Isopropyl alcohol. Safety advice.

Materials Needed:

  • Clear plastic bottle with cap
  • Isopropyl alcohol* (we used a 70% alcohol to 30% water mix)
  • Pump* (if your pump has a bung attachment you wont need the optional material)

(Optional material) - if you haven't got a bung attachment to fit in top of bottle

(Optional tools) - if you haven't got a bung attachment to fit in top of bottle


If you have a bung attachment you don't need the optional materials and can move onto the experiment. Also if you don't have access to Isopropyl alcohol you could use warm water instead, you'll just have to put in more. If like us you don't have a bung attachment then you'll have to improvise, here's how we did it.

Take a pen and remove the inside piece and cap, leaving just a tube. If the pen tube is the type with a small hole about half-way down it, you may need to tape over it.

Now drill a hole in the plastic cap big enough for the pen to fit through. Push the pen through the cap so the nib (the thin end) is pointing up out of the lid, as this is what we'll attach our pump too. The hole should allow the pen through, but be snug enough that it jams the pen near its thicker end.


  1. Pour a small amount of your Isopropyl alcohol into the bottom of your bottle and screw on the cap.
  2. Give the bottle a bit of a shake to agitate the alcohol.
  3. Attach your pump to the top of the pen and start to pump between 15-20 times. If you like you can start with only a few pumps and check the results. When you've reached your desired number of pumps, quickly remove the pen, you should noticed a cloud has formed in the bottle.
  4. The greatest visible results come from a high pressure and a quick removal of the top connection. This quick release of the pressure is what's causing our cloud to form.

How Does It Work?

Water molecules are present in the air all around us in a form called vapour. Under normal conditions these molecules go about there way, bouncing about the atmosphere and wont usually stick together.

Pumping these molecules together in the bottle causes them to compress with each other. The quick release of this pressure allows the air to expand again, resulting in a drop of temperature - similar to as we explained in the DIY Freezing Kit project. This cooling allows the molecules to stick together and condense, forming tiny droplets of water. These tiny droplets of water are what make up our clouds.

The reason Isopropyl alcohol is used instead of just water, is that it gives better visual results. Alcohol molecules have weaker bonds than water (evaporates quicker), so there are more molecules present in the bottle. The more molecules in our bottle, the more there are to condense and form droplets, making our cloud.

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