Mixing-length parameter dependence on the stellar effective temperature for three values of metallicities (M/H = [−0.5, 0.0, 0.5]) and a surface gravity of log g = 4.5. The solar mixing-length parameter (α_⊙ = 1.25) is taken from Kurucz (1993). Different colors correspond to different metallicities, as described in the legend. Horizontal dashed lines show the α values that are used in computations outside the region of effective temperatures for which the mixing-length behavior was derived by Viani et al. (2018).