The ellipsoidal discharges located at the edge of the wire, i.e., where the center of the ellipse is located outside of the wire diameter, primarily provide information on the vapor layer thickness, assuming that the discharge stretches from the electrode to the electrolyte. The horizontal width of each edge discharge spot was determined by the difference in the x-coordinate of the left-and rightmost pixels of the fitted ellipses. Fig. shows in blue a histogram of the horizontal width of these discharges in comparison to the histogram of the vapor layer thickness deduced from the videos recorded with background illumination in orange (same data as in Fig. ). The distribution of the vapor layer thickness deduced from the shape of the discharges (blue) shows a maximum just below 0.2 mm. At small discharge lengths/thicknesses small deviations originate from the evaluation, where spots with sizes smaller than two pixels (0.125 mm) were omitted. The distribution of discharge widths is skewed somewhat towards larger distances compared to the vapor layer thickness in the region of intermediate widths In the images, the electrode outline is indicated by a white line. For all distributions, the bin size is 0.01 mm. (0.2 to 0.4 mm). The shift could be caused by discharges located between the edge discharges and the the center discharges, where the center of the ellipse is located outside of the wire perimeter, but the lateral extent still overlaps with the wire. Many of the largest discharges, such as spot H in Fig. , extend to positions far away from the wire edge, which is most likely caused by a discharge with a large diameter wrapping around to the front of the wire. Overall, the distribution is narrower than for the discharges in the center in Fig. . This means the discharges parallel to the electrode surface are larger than those perpendicular to it, i.e., the discharges are predominantly oblate spheroids (D2 in Fig. ). Most importantly, the distributions of the width of edge discharges correlate nicely with the thickness of the vapor layer.