Recombination temperatures as a function of T_O   iii for models that consider metallicity inhomogeneities as discussed in Sect. 4.3. Along each sequence, only the metallicity varies (see legend for values of Z_A and θ). In no model does differs from by more than 3%. All four sequences from Fig. 5 with varying contrast θ are included as well as the seven sequences from Fig. 6 with θ = 1.0 (color–coding and nomenclature remain the same, see legend). An open circle indicates the position where w_i = 0.5. The ionization parameter is U = 0.01 throughout.