Radial variations of the blue and the red hump positions and of the blue-red hump distance. Left panel: continuum intensity map. Right panel: distance of the red and the blue humps (gray and black solid lines, respectively) from a zero-velocity reference for the first spectral line as well as the distance between them (dashed line) versus the geometric distance from the sunspot center (radius). Each data point in the right panel illustrates the average of the quantities in the defined white rings in the left panel. Error bars show the standard deviation of each quantity in each ring.