Get access

On the theory of electromagnetic scattering from a raindrop splash

Authors

  • L. B. Wetzel


Abstract

Electromagnetic scattering from a raindrop splash on a water surface is examined in terms of the splash structures that have been disclosed by high-speed photography. Of the three basic scattering features, the “crown,” the “stalk,” and the “ring wave,” the first two are modeled as dielectric cylinders, while the third is treated by a perturbation approximation. Cross-section predictions based on heuristic application of these models are found to be in good agreement with laboratory measurements of individual splash-scattering events. A statistical model in which surface slope and stalk height distributions are taken into account is proposed for extending these results to natural rain on a real water surface. Unfortunately, there is at present insufficient experimental data to allow a reasonable test of the theory. Nevertheless, a few qualitative conclusions can be drawn from the formalism: the major scattering feature is the stalk, and while the vertically polarized returns will have only a weak dependence on rain rate, the horizontally polarized returns will depend strongly on both the rain rate and the shape of the stalk (or drop) size distribution curves.

Get access to the full text of this article

Ancillary