Cloud chambers let you see paths left by radioactive particles as they ionize a supersaturation of chilled alcohol vapor.
They need to be very cold (about -15°F) – so most designs require dry ice.
I came up with a design that uses electronic peltier coolers – no dry ice required!
See Make a Cloud Chamber using Peltier Coolers (Instructable) for full details on making your own for about $100.
