Dust and gas temperature derived using the Meudon PDR 1.5.4 code for a plane-parallel isobaric cloud illuminated from only one side. The plotted dust temperature is a weighted average of the dust temperatures calculated for different grain sizes, assuming a grain size distribution, n_gr ∝ a^−3.5 (Mathis et al. 1977), where n_gr is the number of grains with size a, and the minimum and maximum grain sizes are given by a = 10⁻⁷ cm and 3 × 10⁻⁵ cm, respectively. The incident UV flux and thermal pressure of each calculation are indicated in the panels. The values have been selected to represent the physical conditions in Taurus (χ_UV ~ 5), Perseus (χ_UV ~ 25), and Orion (χ_UV ~ 50), where χ_UV is the incident UV field in units of the Draine field (Draine 1978).