Absolute magnetic field strength plotted at the central yz plane (x = 0.0 Mm) intersecting the middle of the flux tube. Upper panel: emerging segments of the flux tube becoming compressed below the photosphere (t = 140.0 min). Middle panel: initial emergence of the field above the photosphere, leading to the formation of two magnetic lobes which extend into the corona (t = 175.7 min). Lower panel: later evolution of the two magnetic lobes, where they have further expanded, compressed against each other and eventually interacted (t = 214.2 min).