Stokes I, V/I, Q/I, and U/I profiles of the Ca I 4227 Å obtained through the RT calculations described in the text. In this figure and those shown below, a LOS with μ = 0.1 is considered, and the magnetic fields are taken to be horizontal and contained in the plane defined by the vertical and the LOS. The FAL-C atmospheric model has been used for the calculations and field strengths between 0 G and 200 G are considered (see legend). The vertical lines indicate the wavelengths introduced in Capozzi et al. (2020), corresponding to rI (red), bI (dark blue), bII (blue), and bIII (cyan). A narrower spectral range is considered for the panel showing the Stokes V/I profile. The positive reference direction for Stokes Q is taken parallel to the nearest limb.