Magnitude of the different terms contributing to the force balance given in Eq. (6) as a function of the mean magnetic field in the umbra at log τ = −0.9 (left) and of the area of the spot (right). Blue squares: gas pressure (P_g), red circles: magnetic pressure (), green diamonds: curvature integral (F_c/8π), and black triangles: pressure required for sustaining the Wilson depression provided by the divergence method. All terms are umbral averages at log τ = 0. Also shown are the correlation coefficients between the various terms and the mean magnetic field in the umbra (left panel) or the sizes of the spots (right panel).