Horizontally and time-averaged profiles of the conductive flux F _c and convective flux F _T as functions of z. The three cases correspond to values of κ equal to 4 × 10 ⁻⁴ (solid, black lines), 2 × 10 ⁻² (dashed, green lines), and 1.2 × 10 ⁻¹ (dash-dotted, yellow lines), respectively.