Cloud-Making: A How-to Guide
Ever looked up at the clouds and thought “I wish I could have one of those”, or breathed out on a cold morning and tried unsuccessfully to catch your visible breath? Well, with a few household objects, you can make you can make a cloud all for yourself!
What you’ll need:
- A plastic bottle (eg. a disposable water bottle or soft drink bottle)
- A ball pump (with the needle)
- A spray bottle
- Methylated spirits (metho)
- Duct tape
- Blu-tac (or similar)
- A love of science!
With this equipment, you’ll be making clouds in no time!
Where do I start?
- Firstly, pour some of the metho into the spray bottle. Point the nozzle inside your chosen plastic bottle and let loose a few squirts.
With this step, you are filling the container with tiny particles of metho. These small, little particles will act as condensation nuclei, or aerosols. We need the water vapour in the air to condense – to change from gas to liquid – onto something. Metho particles will work superbly for our experiment.
Clouds form when ‘parcels’ of air rises up into the atmosphere, where they experience lower pressures. To try to counter this change in pressure, the molecules in the parcel will expand, which cools it down. This cooling will continue until the parcel reaches the dew point temperature, where the water molecules in the atmosphere are moving slow enough that they start to condense onto the tiny particles – the condensation nuclei – in the atmosphere. And so, a cloud is born!
- Place a long piece of tape of the top of the bottle – make sure the lid isn’t on. Your piece of tape should completely cover the opening of the bottle and should provide a good seal. You should use a long piece, but leave a section of the tape hanging off the bottle so that you can use it to rip the tape off quickly.
We need to create a seal around the opening of the bottle, as we need to be able to increase the pressure inside it. But we also need to create a rapid change in pressure to cool down the molecules inside the bottle quickly enough that they reach the dew point temperature and start to condense. This is why we need a section of the tape hanging off; ripping the tape off quickly will mean the pressure inside the bottle drops fast. This part of the experiment is where it may go wrong. If you can’t get a nice cloud forming, try again, and ensure you have a good seal, and a fast tape-rip!
- Place the Blu-tac on top of your tape. Make sure it is a decently-sized blob! Now, poke the needle of the through the Blu-tac – that way, the seal is kept nice and tight.
- Begin to pump! You may need to hold the Blu-tac in place – as you increase the pressure, it will try to escape!
- Once the bottle is a suitable pressure – you will need to experiment to find out for how much pumping is required depending on the volume of your bottle – then rip off the tape! A cloud will have formed inside your bottle as the moisture in the air condenses onto the metho particles!
Congratulations! You have successfully made yourself a personal little cloud! It probably won’t last long – why do you think that is? Comment your ideas below and we can explore what happens next!