The Rayleigh‐Taylor instability is not damped by recombination in the F region

The collisional Rayleigh‐Taylor instability plays a crucial role in explaining the onset and development of equatorial spread F. A number of linear and nonlinear analyses of the instability have been developed for the F region that include recombinative damping. It has been argued that recombination damps the unstable density perturbations and provides a mechanism to suppress the onset of instability or saturate the instability via mode coupling. We show that F region recombination, in fact, does not damp unstable density perturbations relative to the background ionosphere. Recombination acts to reduce the total electron density, both the ambient background and the perturbation, at a rate VR.