Scaled-to-median Ca I column density variations at 4226.728 Å, in green, compared to Ca II-K (in blue), Ca II-H (in red) and Fe I variations (black). Absolute values for Ca I column densities are reported in Table 8. The median of all datasets was shifted to 0. The size is proportional to the number of observed nights for Ca II, while it is proportional to S/N for Fe I and Ca I, as given in Tables 7, 4, and 8, respectively.