All three large-scale velocity components , , and before (t/τ_td = 0.5), at (t/τ_td = 1.0), and after (t/τ_td = 4.3) the occurrence of the bipolar regions (compare with Fig. 4) in the xy plane for Run A5. The vertical velocity is plotted as red (downflows) and blue (upflows) and are normalized by the u_rms in the bulk of the turbulent layer (z ≤ 0). The horizontal components of the velocity field are shown as arrows, where the lengths corresponds to the strength of the flow. Additionally, the contours of negative horizontal divergence is plotted in green for all three times. The yellow contours in all plots show the magnetic field at the time (t/τ_td = 1.0) to guide the eye to the location of the bipolar region formation.