Leftpanel: temperature stratification of the hydrodynamic model solar atmosphere used in this work; also shown is the temperature stratification of the temporally and horizontally averaged ⟨3D ⟩ model solar atmosphere. Vertical lines are used to indicate the locations of the peaks of the temporally and horizontally averaged contribution functions at different inclinations. Right panel: contribution functions to the absolute intensity depression for the individual components of the O I 777 nm triplet and at different inclinations, calculated on the full 3D model solar atmosphere and subsequently temporally and horizontally averaged. The contribution functions have been normalised individually, such that the area under each is equal to unity.