Comparison of observed and predicted cumulative line ratios: [NeII]/[NeIII] (top), [O I]λ 63.2 μm/[C II]λ 157.7 μm (middle), and H₂ S(1) 17.0 μm/H₂ S(2) 12.3 μm (bottom), as a function of A_V. The blue background highlights the observed line ratio of [NeII]/[NeIII], with values between 1.10 and 5.25 (data from Donahue et al. 2011, Egami et al. 2006, and Johnstone et al. 2007). The observed line ratio [O I]λ 63.2 μm/[C II]λ 157.7 μm ranges between 0.22 and 1.64 (values from Edge et al. 2010, Mittal et al. 2011, 2012, and Werner et al. 2014), and is shown in green, and the yellow background highlights the observed ratio of the two pure rotational H₂ lines, between 0.2 and 0.9 (values from Donahue et al. 2011, Egami et al. 2006, and Johnstone et al. 2007). Column on the left: predicted ratios for models with v_tur = 10 km s⁻¹ and solar metallicity, central column: predicted ratios for models with G_X = 10 and solar metallicity, and column on the right: predicted ratios for models with v_tur = 10 km s⁻¹ and G_X = 10.