Formation of bipolar regions for two different field inclinations, left-hand side with purely vertical field (Run V) and right-hand side with y-z inclination (Run INC). Top row: the same as in Fig. 2, but for Runs V and INC. The straight green line for Run V illustrates the exponential growth of the energy in the vertical large-scale magnetic field. Bottom row: normalized vertical magnetic field B_z/B_eq plotted at the xy surface (z = 0) at times when the bipolar regions are the clearest. Run INC is shown for an early time (t/τ_td = 1.8) and a later time (t/τ_td = 4.0) to illustrate the change from a bipolar to monopolar structure.