Characteristic amplitude of δρ/ρ, , for the models with mild turbulence M ~ 0.5 and varying conduction. From top to bottom curve (black to bright red): f = 0,   10^-3,   10^-2,   10^-1,   1. The level of density perturbations is linearly related to the Mach number, δ ~ A(k)_δ,max ≃ 1/4   M. Strong conduction globally damps perturbations by a factor of 2−3, steepening the spectrum towards ∝k^− 1/2 (from slightly shallower than Kolmogorov in the f = 0 run). In the weakly conductive regime, the threshold for A(k)_δ decay is again P_t ~ 100.