Vertical profiles of equilibrium temperature (a) (Avrett & Loeser 2008), the mass density of ions (dotted) and neutrals (dashed) (b), bulk Alfvén speed (c), and sound speed (d) in the two-fluid model of the solar atmosphere for initial magneto-hydrostatic equilibrium configuration. Initially (i.e., at t = 0 s), the temperature of ions (T_i) and neutrals (T_n) are considered to be equal, but later on, this assumption is relaxed, and T_i, T_n are permitted to vary.