Deformation of a liquid drop into a spheroid can produce bright far-field scattering patterns that are not present for a sphere of the same liquid. As reviewed here, these patterns may be analyzed using the methods of catastrophe optics. The enhancements are typically associated with a merging of more than two rays and are therefore a generalization of the rainbow. The patterns may be useful for computational benchmarks and a novel calculation shows that the enhancement of the irradiance may be significant in comparison with ordinary rainbow scattering for ka as small as 50. A related enhancement in the scattering by tilted cylinders is also reviewed.
Marston, P. L. (1999, September). Catastrophe optics of spheroidal drops and generalized rainbows. Journal of Quantitative Spectroscopy and Radiative Transfer. https://doi.org/10.1016/S0022-4073(99)00023-0