Synthetic observables calculated for the first snapshot in the series. Top left: Continuum image at 517.2 nm. Top middle: Nominal line core of the Mg I b2 line. Top right: Nominal line core of Fe I 525.0 nm line. Bottom left: Spatially averaged spectra of the considered spectral lines, Fe I lines are shifted for clarity. Bottom middle: Circular polarization in the wing of the Mg I line. Bottom right: Circular polarization in the wing of the Fe I line. The upper-row panels are shown in units of the mean quiet-Sun continuum.