The simulation of weather phenomenon is important to the visualization of weather information. The cloud simulation is a key to realize the simulation of weather phenomenon. Three effective algorithms for generating still clouds and moving clouds are presented, which have greatly improved the currently used simulation approaches. The recursive computation algorithm is used instead of the circulatory computation for making still clouds, which improves the running speed. The arbitrary-length clouds can be obtained by the non-repetition cloud generation algorithm. The cloud smooth algorithm improves the structure of clouds and makes the movement of clouds continual and stable. The algorithms provide a good reference for weather information visualization.