|MadSci Network: Chemistry|
Hi Erica, The cloud on the stage at concerts (and other theatrical performances) is produced by a "smoke machine". What this machine does, is take a specially made smoke fluid (usually a mixture of water and glycols), and heat it up so that it vapourises into a gas. It then blows this gas out onto the stage, where it then cools down and condenses into the white smoke. It is, in a way, similar to a pot of boiling water on a stove. Next time you're in the kitchen, you may notice that the "steam" from a pot of boiling water is actually condensed water vapour, in the same way that the white smoke is condensed smoke fluid vapour. I hope this explanation has helped. Jonathan Feldman University of Western Sydney, Nepean
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