Gas-temperature distribution with vertical logarithmic optical depth in the 3D model atmosphere (blue). The T − log τ relation of the corresponding 1D model atmosphere is also shown (orange). The full widths at half maximum of the line-profile’s integrated, 1D, non-LTE contribution functions to the line depressions (Amarsi 2015) are shown for the diagnostic S I lines (the line-averaged result is shown for the S I 1045 nm triplet). These are presented for both the disc-centre intensity (black) and disc-integrated flux (red) with circles indicating the positions of the peaks.