Drawing on Steam

When I used to drive around in the back seat of my parents' car in the rain, I used to stare intently at the falling rain on the window and pretend that it was a meteorological map and I would silently play weather forecaster.  The other day my son starting drawing with his finger in the steam that he puffed out onto the cold window.  He pointed out the tiger and the bunny that he drew and he huffed out more hot air to create a new drawing.   Drawing with condensed air, playing with falling raindrops, what other mediums am I passing over for flashier, more expensive materials?

Check out another fascinating material, Laura Fields' Smoke Painting website.