(See diagram) Presupposing that a Rocheworld can even exist...
I imagine that sunlight would work more or less the same in the atmosphere of any part of an Earth like planet that was tidally locked with a duplicate planet in a Rocheworld scenario. But what about in the area between them, where the planets share atmospheres?
An atmosphere traps the sun's rays and that's why we get day light and heat etc. But that's also because the surface of the planet is bouncing it back too, right? But the area of shared atmosphere in Rocheworld does not have solid ground, so the light would go right through. What does that do for light, visibility, warmth, radiation, etc?
For arguments sake lets say that the planets are angled somewhat so both the planets can get sun rays.