Left: stratification of the background atmosphere (temperature (T), density (ρ), gas pressure (P_g)) and the initial magnetic field distribution ((P_m) is the magnetic pressure) at t = 0. Middle: the colored contours show the distribution of the vertical component of the magnetic field at the photosphere (yellow is positive and blue is negative). The blue and red field lines represent the outer and inner-most field lines of the emerging tube. The white field lines belong to the pre-existing field. The direction of the field lines is shown by the arrows. In this case, the two fields into contact are almost anti-parallel. Right: the same for an experiment where the field lines are at an angle of about Φ = 90. At this time of evolution, efficient reconnection has not started yet.