Convective velocities measured in the Ba ii line as a function of magnetic field strength obtained from the Fe i lines. Left panel: unsigned values of the velocity, all pixels are considered. The three group of points correspond to the velocities at three levels of the Ba ii profile, larger points mean higher in the atmosphere (0, 400 and 650 km, approximately). Middle: only granular points, velocities at the deepest level of the atmosphere. Right panel: only intergranular points.