Mesh simplification algorithms play an important role in computer graphics. In particular, view-dependent simplification methods are utilized widely to reduce the geometric complexity of large outdoor scenes. The so called continuous level of detail technique, for instance, is prevalent in the area of terrain rendering. In this paper we apply the latter technique to the more general volumetric case. We propose a volume rendering algorithm, which constructs a hierarchical tetrahedral mesh from regular volume data in a view-dependent fashion. The popping effect which generally arises from view-dependent algorithms is addressed by a new fast method for the smooth interpolation of the mesh hierarchy. We demonstrate the performance of our algorithm by displaying clouds in real-time. Here, the application of the pre-integration technique allows for a wide range of cloud appearance and guarantees accurate compositing. Additionally, we show how to utilize our algorithm for the accelerated display of ground fog in terrain rendering scenarios.