Modes corresponding to the neutral viscosity (blue lines), ion-neutral collision scale (orange lines), and neutral-ion collision scale (green lines) as a function of height, computed for the original density profile (solid lines), for the enhanced density profile (dashed lines), and for the enhanced density and magnetic field profiles (dotted lines), from Eqs. (33)–(34). The horizontal dashed line marks the maximum mode number shown in Fig. 5, n = 48, and the dotted line represents the largest mode number that can be resolved in the domain, using two points, n = 256.