Shadow of Steam: Seeing the Unseen

[Manraj singh]

My mother was ironing clothes a few days ago, and the iron was really hot. It was giving out steam, i couldn't see it, but i could see its shadow on the wall. How so?

 

[Drakkith]

I believe it is caused by the refraction of the light going through varying pockets of cold and hot air/steam. The different pockets lead to some light being refracted more or less than others and forming a wavy pattern of dark and light areas on the wall.