Top panels: abundance profiles obtained with the model with constant ζ₂ = 1.3 × 10⁻¹⁷ s⁻¹, with no initial cloud evolution (model , solid curves) and with a cloud evolution of t_CE = 10⁶ yr to set the initial conditions (dashed curves). The different colours refer to the four time steps investigated in this work (labelled in the first panel, in year). Bottom panels: ratios between the abundance profiles of the model with and without cloud evolution. The colour code is the same as for the upper panels.