Panel a: magnetic configuration of the simulation domain with physical size of 24 × 24 × 16.8 Mm at t = 180 s after the non-equilibrium ionisation of hydrogen has been switched on. The colour of the individual magnetic fieldlines corresponds to their temperature. The 5 × 10⁻¹² kg m⁻³ density isosurface is shown in blue. Several cool and dense condensations have formed at coronal heights. Panel b: line-of-sight component B_z of the photospheric magnetic field at z = 0. Panel c: variation of the magnitude of magnetic field strength in vertical direction at y = 12 Mm. An animation of this figure is available online.