Number densities of Fe i, Fe ii, and CH (top-down), plotted versus τ_Ross for the three model atmospheres of a red giant: 3D hydrodynamical (gray scales showing the logarithmic probability density of the 14-snapshot ensemble), average ⟨3D⟩ (solid line, 14-snapshot ensemble average), and 1D LHD model with α_MLT = 1.0 (dashed line). The number densities of Fe i and Fe ii are provided as fractions of the total iron number density, n(Fe_tot), whereas that of CH is given on a scale where n(H_tot) = 12.0.