The vapor layer thickness D, i.e., the distance between the electrode and the vapor-electrolyte interface, was determined line by line for all vertical positions on either side of the electrode in all frames. First, we show in Fig. that the average vapor layer thickness along the wire increases from the tip upwards to the electrolyte surface (average thickness at the bottom is 0.15 mm and at the top 0.3 mm). The distribution is similar on either side of the electrode. This increase in vapor-layer thickness can be rationalized by the buoyancy of the gas produced mainly by electrolyte evaporation, as explained in the SI in Section S4. There is no significant difference in vapor-layer thickness between the side close to the counter electrode (right) and the opposing side (left), indicating that the electrode arrangement does not affect this property.