shock heating. The results for $\tau$ using the temperature based criterion are shown in Figure \[fig:tau\_eff\].

The status of the shocked cloud gas is somewhat ambiguous in the model, however since it is overpressured when shocked and some of it re-expands and cools adiabatically at later times below X-ray emitting temperatures. For clouds shocked by slower shocks, only a surface layer is raised to X-ray emitting temperatures. Thus, at later times, the removal of material from clouds is primarily by thermal conduction and cloud evaporation as discussed by WL does apply.

We expect that the evaporation timescale for the remnant as a whole should depend in a similar way to that for individual clouds [though see @Balbus_1985 regarding the effect on evaporation rate of a collection of clouds]. For “classical” evaporation, i.e. cloud evaporation when the heat flux is far from saturation, the evaporation timescale goes as $t_\mathrm{evap} \propto R_\mathrm{cl}^2 n_\mathrm{cl} T_h^{-5/2}$ where $R_\mathrm{cl}$ is the cloud radius, $n_\mathrm{cl}$ is the cloud density and $T_h$ is the temperature of the hot gas far from the cloud. In the case of highly saturated heat flux, which is the more typical condition in SNRs during the non-radiative phase, we get $t_\mathrm{evap} \propto 