Galactic 21 cm H I profile in our line of sight towards NGC 7469, of brightness temperature as a function of velocity, from the LAB survey (black dots). The red line is the Gaussian function (Eq. (A.1)) used to determine the velocity dispersion σ_v and the velocity mean μ. Estimates of these two parameters were obtained by averaging the values from the LAB (Kalberla et al. 2005) and EBHIS (Winkel et al. 2016) surveys. The average velocity dispersion is used as the turbulent velocity for the Galaxy in the HOT components; see text for details of this argument.