Variation of vertical (top) and radial (bottom) velocities with high-pass filter C i 5380 continuum intensity for spines (left) and inter-spines (right) in the interior penumbra (radial zones 2:4). Plus symbols correspond to measurements in the 5380 line, squares to the 6301 line, lines drawn full to COG measurements, short dashes to line core, and long dashes to 70% bisector (6301 line only) LOS velocities.