A cloud chamber is essentially a device that enables the detection of charged particles. The particles displace electrons from the molecules in a supersaturated vapour (one that's at a pressure that would normally cause it to condense). This creates a trail of 'mist', made up of tiny droplets of liquid; the trail persists for several seconds as the droplets fall through the vapour.
Atmospheric mist is similarly created by the condensation of supersaturated water vapour as the air cools.
Among the discoveries that have been made in cloud chambers are those of the positron in 1932 and the muon in 1936, both by the American physicist Carl Anderson – who in 1936 was awarded the Nobel Prize in Physics for his work in this field.
© Haydn Thompson 2018