as representatives of late-time accretion of material in an ongoing process of galaxy buildup by mergers [@MI94b; @Blitzetal99; @Manning99]. Because they evolve at an earlier time and closer to the centers of the parent galaxies, however, the WFC’s would evolve in an environment of higher pressures and UV fluxes, compared to either Lyman-$\alpha$ clouds or HVC’s. Their environment may, instead, more closely resemble that of cooling flows (e.g. Sarazin 1986; Loewenstein & Mathews 1987; Sarazin & White 1987, 1988), and many of our results may have relevance to those systems. Additionally, the Ly-$\alpha$ clouds have been proposed as being contained within dark matter “minihaloes,” (e.g. Rees 1986; Ikeuchi 1986; Mo, Miralda-Escude, & Rees 1993) whereas the WFC’s are either pressure confined, or at most weakly self-gravitating

In this paper, we verify our basic conjecture that most of the gravitational energy released by the infalling WFC’s is dissipated within the RHG. That process is crucial to the assumption that the RHG is in quasi-thermal equilibrium. Without this heating source, the background gas would gradually be depleted due to loss of thermal energy and precipitation into WFC’s. A reduction in the pressure of the background gas would also enable the WFC’s to 