SCATTERING OF LIGHT BY SMALL DROPS OF WATER

Abstract

When very small drops of water increase in size until their diameter is one-fourth of the wave-length of the incident light (2a/λ = 1/4), they scatter the light essentially according to Rayleigh's law for non-conducting particles. But when the diameter increases from λ/4 to λ/2, the intensity of light scattered along directions that point toward the source decreases almost to zero, the change being most marked between 2a/λ = 1/4 and 2a/λ = 3/8. The sharp increase in the proportion of scattered light with an increase in size, according to the sixth power of the radius, continues however in the directions along which the main part of the scattered light is radiated by the particle. As the scattering begins to deviate from that given by Rayleigh's law, colours other than blue appear with great strength; the dispersion of the colours increases with increasing size of the particles until mainly red light remains.