On the physical explanation of the Perkins instability

Perkins' instability theory (1973) provides a reasonable theoretical explanation for the midlatitude ionospheric spread-F phenomenon. Although his derivation process and model are correct, the physical explanation provided can be improved. In this paper a plasma motion-balanced view of the Perkins instability is provided as an improvement to the Perkins force-balanced explanation. We derive the growth rate equation with neutral wind present and show that the new approach yields the same growth rate equation given by Perkins (1973) when the neutral wind is zero. Additionally, a new mathematical approach yields the same result and identifies the source term of the instability.