Electromagnetic scattering by high-density meteor trails

The discussion first concerns itself with establishing limits on the validity of the low-density approximation. These depend not only on the electron line density (as has sometimes been loosely stated) but also on the wavelength of observation and on the altitude of the trail. Next, a model is developed for scattering by a supercritical density distribution of electrons, based on the idea that the process can still be viewed as a superposition of individual Compton effects, but with the wave incident on the electron attenuated because of refraction (in analogy to the skin effect). Results of this model are compared with those obtained by the usual approach of replacing the electron distribution by a metallic scatterer whose surface is the critical density contour. Some calculations with nonGaussian electron distributions help to clarify the physical interpretation.