Response functions integrated over wavelength, added up for all four Stokes parameters and plotted as a function of the logarithm of the optical depth log τ₅. Top-left: response to the temperature T. Top-right: response to the line-of-sight velocity v_los. Bottom-left: response to the magnetic field strength B. Bottom-right: response to the inclination of the magnetic field with respect to the observer’s line-of-sight γ. Different colors correspond to different spectral lines. Green: 15 648 Å, red: 15 652 Å, blue: 15 662 Å. The response functions are calculated with the atmosphere resulting from the two-component inversion shown in Fig. 6.