Variation of energy density with height. Top: energy density equivalents corresponding to velocity (red line with pluses), intensity (purple-dash-dotted line), and temperature rms fluctuations (black-solid line). The black-dashed line shows results for the temperature rms fluctuations when using the gas density in the original HSRA model. The blue line indicates the gas density in the modified HSRA model. Middle: energy gradient per km in height assuming a propagation with v_ac. The red line shows results from using a net cooling rate of 100 W g^-1 (CL12). Bottom: radiative losses in the units used in CL12.