Well. You could do something like a bunch of seperate segments lined up across the screen and set to be moved down with their figure but that would look odd. Even if you did 2 or more it would look odd with the amount of consistancy that creates a thought that the raindrops are all one thing. But if you want to do something like that in SN, make a bunch of segments with gradients from a bright blue to white then add a perfect amount of blur then add a bunch of those figures onto the frame then by every frame, move them down and make sure you have another set of raindrops ready to drop when the ones in view are about to create gaps.