Schematic sketch of the dipole field in the sunspot magnetic field. The geometry allows one to estimate the formation height of the measured Stokes-V parameter of the spectral lines in the sunspot regions. The line-of-sight vector is characterized by angle Θ. Δx₁ and Δx₂ are the distances of the Stokes-V zero line between neighboring spectral lines. Δh₁ and Δh₂ are the real height of the spectral lines.