Most people in the world know what rain is, and a great deal of those people have tried seeking shelter in a café with a hot cup of coffee, tea or chocolate, while staring at the rain pouring down outside.
There is nothing like rain to bring a melancholic attitude with it, and I personally believe that rain is one of the major reasons people start writing. Somehow rain just inspires to it.
This is an exercise for those moments. It's easy, soft and emotional, and it goes extremely well with hot beverages. I also recommend using pen and paper for it. It's just easier being melancholic that way.