Histograms of velocity dispersions: σ_therm (top), σ_turb (middle) and σ_tot (bottom). On each panel, the different curves represent subsample of pixels selected according to their temperature: all pixels (black), the WNM (T> 5000 K, dark blue), the unstable gas (200 K<T< 5000 K, blue) and the CNM (T< 200 K, light blue). All quantities were computed using a high resolution simulation (1024³ pixels) with the following initial conditions: n₀ = 2.0 cm^-3, ζ = 0.5 et v_S = 7.5 km s^-1.