Same set of magnetic field lines from Figure 5, but this time every individual set of six field lines was cut at the apex by a plane perpendicular to the direction of the field at the central field line. We define the apex as the point along a flux tube where the field strength is minimal and therefore the cross-sectional area of the flux tube is maximal. (These plots may be viewed from different angles in the animations available in the online materials.)

(Animations (6a and 6b) and color version of this figure are available in the online journal.)