Reverse/Inverse Shadows for Selected Material

I am new to Unity and I am trying to invert the shadows of my cloud material. I plan on rotating the clouds, so I can't simply edit the clouds to make the section of the clouds on the dark side of the earth black. Secondly, because of the directional lighting, the section of the clouds that are on the bright side, are black because I flipped the normals of the mesh. If you can please let me know how I could make this work. Here is an image of my earth, in case my explanation was hard to understand:

Thank you.