Scattering of visible light by large water spheres.

The intensity and the degree of polarization of the radiation scattered by a large sphere were computed using the Mie theory at sufficiently small interval of the scattering angle for obtaining a complete picture of all the characteristics of the field of the scattered radiation. The results are presented for four different sizes of the water sphere (radius = 6.25 micro, 12.5 ;micro, 25.0 micro, and 50.0 micro) assumed to be illuminated by an unpolarized beam of monochromatic radiation with wavelength 0.4 micro. A detailed comparison is then made between the results obtained using the exact Mie theory and those obtained using an approximate approach based on the application of the other laws of the geometrical and physical optics. The angular positions of the primary and secondary rainbows, as well as those of their supernumerary bows as obtained using the approximate method, agree with those obtained from the Mie theory only if the size parameter of the sphere is of the order of 800. Besides the phenomenon of glory which is not amenable to explanation in terms of the geometrical and physical optics, the Mie computations bring out several distinct maxima and minima whose occurrence cannot be explained in likewise manner.