Interference rings can be observed in mirrors clouded by condensation, even in diffuse lighting. The effect depends on individual droplets acting as point sources by refracting light into the mirror, so producing coherent wave-trains which are reflected and then scattered again by diffraction round the same source droplet. The secondary wave-train is weak but still capable of modulating the primary to give a circular interference pattern centred on the image of the observer's eye, regardless of the direction of the incident light.