From top to bottom: time progressions of the current density; the dominant component of the convective inertia, ; and the Q-value. Superimposed on all plots is the in-plane magnetic field, and panels g), h), and i) also show electron velocities as well as coloured areas where the Q-value is greater than zero, indicating the existence of a vortex. The lengths of the arrows next to the plots represent the greatest speeds reached, in each panel approximately 0.22c, i.e. 2.2v_ae0. The simulation times, indicated at the top of each panel, were chosen around the occurrence of island and vortex formation.