Column density distribution of the synthetic observation of the KHI on the right side of Fig. 17 at t = 40, as shown in black. The column density is shown in code units. The central part of the distribution is fitted with a log-normal distribution, as shown as the dashed red line. A power-law tail is seen on the high-density side, as well as an additional excess on the low-density side, which is comparable to what is seen in some observations of molecular clouds.