Heating (top panels) and cooling (bottom panels) rates as a function of visual extinction for two models (left: ζ = 10^-16 s^-1; right: ζ = 7 × 10^-14 s^-1). In both models, n_H =100 cm^-3, G₀ = 10 and, on both sides of the clouds, , Z = 3. Figures present profiles from the edge of the cloud to the center. Cosmic ray heating and heating by exothermic reactions do not appear for the ζ = 10^-16 s^-1 model because their rate is always lower than 10^-24 erg cm^-3 s^-1.