Beautiful video of our cloud chamber showing the paths of ionising particles from a radioactive isotope 
We no longer use cloud chambers in research but they still provide great demonstrations!pic.twitter.com/Kt5mQZtaCU
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This is a radioactive source emitting alpha particles
The wispy paths are ionising particles passing through alcohol vapour causing droplets to form
Finding ways to track & analyse the paths of particles has always been key in learning what makes up the universe!
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neat.. so why does ionizing alcohol vapor cause "droplets" exactly? Does Alcohol Vapor minus some electrons induce a phase transition of some sort?
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The alpha particles ionise the alcohol molecules, which then attract other molecules, eventually clumping together enough to form visible droplets. Cloud nucleation around cosmic rays is of interest for atmospheric physics - see e.g. https://home.cern/science/experiments/cloud …
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The alpha particles ionise the air, and the alcohol condenses on the ions to make droplets. It's worth restating (again) that the "cloud chamber" nucleation mechanism is impossible in Earth's atmosphere. Other planetary atmospheres however could have it.
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Oooh I can answer this! The vapor in the chamber is supersaturated, so basically any disturbance is enough to make it "cloud". When ions get made, they attract other vapor molecules, and in a supersaturated solution, this produces the "droplets" we see!
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