Linear polarization angle α (top panel), linear polarization fraction P_L (middle panel), and Stokes V/I (bottom panel) across the Ca I 4227 Å line, calculated in the FAL-C atmospheric model for an LOS with μ = 0.1. The various curves correspond to calculations considering horizontal fields with B_av = 40 G (see text), but different filling factors and field strengths: f = 1 and B = 40 G (dashed line), f = 0.5 and B = 80 G (dotted line), and f = 0.2 and B = 200 G (solid line). The vertical lines indicate the same wavelengths as in the previous figure.