I think that the the coming and going of the rain was something to do with layer animations, but I don't know much about those. However, I do know that we can't create rain using particle effects, like Kemo. I guess one way you could achieve a similar effect with the tools we have available would be animating hundreds of planes with a rain texture on them, but that would be resource-intensive and getting the transparencies to work would be hell. Also, you could try manually grabbing the particles from the prp and putting them into your prp using one of the many programs available to do that- Andy managed to get snow into his age Serine by taking the particles from Delin. He wrote a tutorial on how to do that, I think... if he has, it's probably at GoMA. Could be worth a shot
