Seriously, there may not be many more things that I like to draw more than rain scenes. You really get the opportunity to push the mood, atmosphere, and texture. I used the rain as mainly describing the direction of the light source. It didn't need to be covering the entire panel to communicate the idea that it's raining. Instead, I wanted to show how the rain is interacting with the environment. It's more of a challenge, but much more believable. Then, I would render the rain in the sky closer to where the light source is originating. This would reinforce the idea of a dense atmosphere. Hope you all like!