Vortex cell statistics for Run C. Except for panel a), different heights are represented by brown (z = −90   km), green (z = 0) and blue lines (z = 90   km). Except for panel b), only strong swirls with τ_s < 120   s are taken into account. The dashed and dotted lines represent the subset of vortices with vertical (ι < 20°) and horizontal (ι > 70°) orientation, respectively. The fraction densities plotted in panels b)−f) are normalized histograms, the normalization being such that the integral over all values of the respective abscissa variable is one. Angle brackets  ⟨ ... ⟩  denote the horizontal mean of the respective variable in downflow regions (i.e., where v_z < 0 at the respective height).