Experiment on Sunset Colours

Abstract

EVERYONE is more or less familiar with the coloured halo around a light when viewed through a bedewed window, and the streaks of colour which a cloud of vapour presents in a strong light. The purity of colour in the diffraction halo depends essentially on the uniformity of size of the condensed droplets, and the same remark may be applied to a cloud or mist. It occurred to me that the colours of a mist or cloud could be made more brilliant and extensive by controlling in some way the motion and distribution of the differently sized suspended droplets. I have accomplished this partially by the following apparatus.