[1979] Appl. Opt. 18, 1961-1965, doi:10.1364/AO.18.001961
G. P. Können and J. H. de Boer

The Airy theory of the rainbow is extended to polarized light. The degree of polarization of the rainbow is less than expected from geometrical optics; it increases with droplet size. For a droplet diameter >1 mm the locations of the supernumerary rainbows are equal for both polarization directions, but for a diameter <1 mm the supernumerary rainbows of the weaker polarization component are located between those in the strong component.