Numerical and analytic solutions in the ray-optics region have been obtained for the scattering of HF radio waves by a spherical electron cloud with a Gaussian distribution of electron density in the radial direction. The results show that a highly overdense or hard cloud has a wide range of backscatter angles for which the cross section is almost constant with a value close to that of an equivalent conducting sphere critical radius size. A slightly overdense or soft sphere has a much narrower range of almost constant cross section whose value is proportional to the fourth power of the critical radius and considerably below that of an equivalent conducting sphere.
Revision of report dated 18 Mar 1971. Supersedes report dated Jun 1969, AD0691428. Availability: Pub. in Radio Science, v7 n2 p257-267 Feb 1972.