This paper proposes a simple and computationally inexpensive method for simulation of clouds with cellular automata. The cloud evolution is simulated using cellular automaton that simplifies the dynamics of cloud formation. In addition, clouds contain varying degrees of translucence, and their amorphous structure can change with time. Clouds are then generated due to the phase transition from water vapor to water droplets. Realistic cloud simulation would also be an effective tool in the field of meteorology. By using the cellular Automaton, the distribution can be obtained with only a small amount of computation since the dynamics of clouds are expressed by several simple transition rules. The cellular automata are the new style, high performance simulation tool.