the RHG, such that the cloud retains smaller volume and cross section. Consequently, the cloud encounters a smaller gas mass along the path of its descent, and fragmentation occurs at a greater depth. On small wavelengths, the infalling cloud appears to be better preserved than in the previous models. But on the scale of the cloud size, the cloud again fragments after encountering a column similar to its own mass, as above.

Model 4: Subsonic Sedimentation of WFC’s
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For Model 4, $D_\rho=25$, and $g=0.05$, such that $V_t$ is predicted by Equation \[eq:vterm\] to be subsonic. The evolution of the density of Model 4 is shown in Figure \[fig:mod4rho\]. The cloud rapidly reaches a terminal speed, $V_t\approx0.3$, smaller than predicted if $C_D=1$. As in Model 1, however, expansion of the cloud enhances the drag coefficient to $C_D>1$. The cloud therefore never achieves the terminal speed predicted for a hard sphere, even in the absence of strong supersonic dissipation. From Equation \[eq:rt\], $\omega\approx6$, and the cloud breaks up even more rapidly than the more dense clouds considered in Models 1-3, due to its reduced density contrast relative to those models.

The downward displacement of the cloud in Model 4 is reduced 