Horizontal cuts through a 3D MHD simulation snapshot. Plotted are the electron temperature (top panel), electron number density (middle panel), and magnetic field strength (bottom) at geometrical heights of 650, 900, 1500, 1700, and 2000 km. To enhance the temperature contrast, the displayed temperature range is set to that of the synthetic brightness maps shown in Fig. 2. The range of temperatures is given in the lower right corner of the frames. The field size is 24 Mm × 24 Mm.