Top panel: equilibrium temperature and densities of H, H⁺, H₂, ${\mathrm{H}}_2^{\ast }$, e⁻, C, C⁺, CH⁺, and HeH⁺ obtained for an isobaric (total pressure ~2.0 × 10⁹ K cm⁻³) CLOUDY model with an initial total hydrogen nuclei density n(H_tot) = 3.06 × 10⁴ cm⁻³ as a function of the distance from the star starting from the illuminated face into the depth of the cloud. Middle panel: equilibrium temperature and abundances of species as a function of visual extinction (A_V). Bottom panel: equilibrium temperature and abundances of species as a function of the distance (linear and angular) from the star, starting from the illuminated face into the depth of the cloud.