We propose an efficient framework for dynamic cloud rendering. Base on the proposed simplified lighting model, the Shadow Relation Table (SRT) and Metaball Lighting Texture Database (MLTDB) are constructed in the preprocessing, and features such as selfshadowing and light scattering can be computed quickly using table lookup at the run time. Clouds are rendered using textured billboards and alpha blending, which is further speeded up by incorporating the octree hierarchy and the hierarchical texture caching. Key words: cloud simulation, dynamic clouds rendering, cellular automata