Re: What is the cloud formed on stage during rock concerts?

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