It was in one of the videos that Asobo and MS do and I am pretty sure it was the director that mentioned the way rainbows appear as a consequence of conditions and that they are not artificially generated. To be honest I could spend spend hours wading through videos trying to find the brief 5 second comment he made on this and get nowhere so I wont be bothering. Dont take this offensively but it doesn’t matter to me if you believe what I posted or not, its just what Asobo said and I have no reason to doubt it.