Comparison of PRD treatment in two plane-parallel model atmospheres (left-hand and right hand column respectively) taken from a radiation-MHD model. Panels a) and b) show the temperature (black) and vertical velocity structure (red) of the atmospheres. Panels c) and d) show the emergent intensity in the Mg II  k line, with PRD treated fully angle-dependent (black), angle-averaged (blue) and the hybrid approach (red). Panels e) and f) show a similar profile comparison, but now for the Lyα line of hydrogen. The stars and diamonds in panels a) and b) indicate the τ = 1 height for the wavelengths indicated in panels c)–f), with stars for the Mg II  k line and diamonds for Lyα.