Comparison of observed and predicted ro-vibrational H₂ lines, normalized by Paα, as a function of A_V for the models described in Sect. 2.2. The different background highlights the observed ratios, between 0.1 and 2.3 (values from Edge et al. 2002). For each ratio, the color of the background and that of the corresponding theoretical cumulative ratio are the same. Column on the left: predicted cumulative emission for models with turbulence of 10 km s⁻¹, solar metallicity, and various values of G_X: 0.1 (top), 10 (middle), and 100 (bottom); central column: predicted cumulative emission for models with G_X = 10, solar metallicity, and various values of turbulence: 0 (top), 10 (medium), and 50 (bottom) km s⁻¹; column on the right: predicted cumulative emission for models with turbulence 10 km s⁻¹, G_X = 10, and various values of metallicity: 0.3 (top), 0.65 (middle), and 1 (bottom) Z_⊙.