Aspect ratio H/r of the stellar irradiated outer disc (bottom) calculated using the mid-plane values for discs with constant viscosity and non constant opacity as in Fig. 1 and the corresponding opacity values for κ_R (top). Starting from a flared disc profile the discs are evolved until they reach thermal equilibrium. The different colours indicate different Σ₀-values. The red line represents the outer disc simulation corresponding to the inner disc simulation shown in Fig. 5.