Gas temperatures T (first row) and contribution functions C_ν for the inner wings (0.2 nm redward of the line centre) of the Hα (second row) and Hγ (third row) lines, in vertical slices of the solar metallicity (left column) and metal-poor (right column) model atmospheres shown in Fig. 1. Lighter shading indicates larger temperatures (first row), and more emergent flux contribution (second and third rows). Contours of constant log τ_R are overdrawn. In each plot, the contribution functions are normalised such that their maximum values are unity.