Hmm .. thought about that challenge too. Light ... one could post literally anything into it as light will ever be the main subject of a photo. Someone said once, a photographer is the painter of light ... .. but ok, this is about your shot: i think it fit's perfectly well. Light makes a good part of that image and the lack of light in the other parts makes it interesting. The shape of the clouds building two lines that lead the eye into the sun is just perfect to me.