Created by Julian Vidal, Pixel Snow is aÂ processing script enabling real time snow dynamics by drawing objects and letting snow fall on them. You can adjust density of the snow as well as speed it falls. InÂ additionÂ you are able to create snow vortex (eats snow) and additional snow generators. What may appear as a simple snow generator, once you add a number of objects and generators, can quickly turn into a pretty complex example of collision dynamics.
An open source script you can download here is somewhat a great example of dynamics possible in processing. Go download it and try it yourself in processing.