Abstract: The paper introduces a new, computationally inexpensive, real-time method of simulation of clouds for dynamic particle-based cloud rendering. The method covers such phenomena as atmospheric fronts, stable and unstable balance, thunderstorms, simplified simulation of middle and high clouds, correlation between wind and clouds and even tornadoes. The simulation is based on several simple numeric global parameters, like average temperature and average amount of clouds, which determine the local weather. It is also capable of generating multiple forms of clouds (from stratus through cumulonimbus), which may fluently change during the simulation.