During lightning strikes to aircraft, there is a displacement of the impacted area on the aircraft's surface and the dynamic of the arc root is a key to understanding and predicting the damage produced on the aircraft skin. This work aims at studying experimentally this dynamic with a new method of producing sweeping arcs based on a stationary arc and an electromagnetic launcher propelling aeronautical test samples. The experiments are also achieved with a wind tunnel that blows the arc on the test sample for comparison. After a description of the previous experiments of arc root displacement and a distinction between the cathodic and anodic emission processes, this paper characterizes the arc root physical properties with direct visualization through high-speed cameras and electric measurements for different initial conditions. The results are separated by the arc root polarity and discussed to give an insight into the influence of the experimental conditions on the interaction between the electric arc root and the test sample during swept-stroke. It is shown that for a cathodic arc root, the nature of the displacement—continuous or jumping—highly depends on the current level and the speed of the relative motion between the electric arc and the test sample. For an anodic arc roots, the variations of these parameters provoke jumping modes of displacement with different characteristics.