Overview of some physical parameters on the (x, z)-plane along the horizontal cut depicted by the horizontal line at y ≈ 5.3 Mm in the first row of Fig. 9. From left to right: temperature fluctuation with respect to the box-averaged T(z), ratio between v_x and the local sound speed c_s, ratio between v_z and the local sound speed c_s, and divergence of the velocity ∇ · v. White contours enclose regions where the temperature fluctuation is greater than 1000 K. The black solid line indicates the location where τ_R = 1. The horizontal black dashed line is located at z = z₂ = −0.60 Mm and therefore corresponds to the height of the plane depicted in Fig. 9. Arrows indicate the velocity field in the (x, z)-plane.