Vertical cuts through the model disk from our POLARIS simulation. The cuts show the temperature (K) distribution of large a-C(:H)/a-C at thermal equilibrium (top left), the hydrogen density n_H (cm⁻³) distribution (top right), the radiation field intensity G₀ (bottom left), and the G₀∕n_H (cm³) ratio (bottom right) of the two previous maps. The black lines correspond to 25, 50, and 75% of the total emission at 3.3 μm seen from the top. The white area in the two lower panels arises because G₀ is not defined in the most median parts of the disk because UV radiation does not penetrate them.