Statistical distributions as a function of height z of the number density of swirls per unit area, n_2D (top), the effective radius, r_eff (middle), and the effective period of rotation, P_eff (bottom). The median and the 1σ and 2σ deviations of the distributions are shown at each height z. The average optical surface τ₅₀₀ = 1 (z = 0 km) is marked by a dotted line, while the heights of the surface layers of the convection zone, photosphere, and low chromosphere used in the analysis are indicated by dashed blue lines.