Results of RT calculations considering the FAL-C atmospheric model, for the radiation emerging at a LOS with μ = 0.1. The top panel shows the Q/I profile of the Ca I 4227 Å line as a function of wavelength, obtained in the absence of magnetic fields. The solid curve shows the profile obtained when including the effects of blends, and the dashed curve shows the profile obtained when neglecting them. The colored vertical lines give the wavelength positions of interest introduced in the article (see legend), with bI′ defined in the text. The bottom panels show the linear polarization angle α as a function of field strength, at the various wavelength positions of interest (see legend). These calculations were performed in the presence of a horizontal magnetic field contained in the plane defined by the local vertical and the LOS (see text). The solid and dashed curves represent the results obtained when accounting for the blends and neglecting them, respectively.