Pathlines of closely spaced gas parcels. The coloured curves indicate individual pathlines, starting at t = 0 s at the triangle, and ending at t = 1000 s at the asterix. The pathlines are constructed from seed points at t = 500 s located in the small black squares that have have a side length of 50 km, and are grouped into four areas. From top to bottom: corona, transition region, chromosphere, and convection zone.