The dome. If you do that indoors, you won't get a rainbow, unless there's curved light involved. Prisms are light refracting off of curved glass. Our sky is curved glass. The globe is fake, Nasa is fake. Science has been hijacked by liars. There is no math for bowing water. Look at an earthglobe. See that curved water? There's no math for that. Math doesn't really prove most of the things they assign it to, anyway. Math really only proves the equations of the numbers calculated. It's completely irrelevant to what our senses and logic tell us. They just use it to stump the common people into conceding to whatever they say. And you end up believing what the thought purveyors say to believe, over what your eyes and logic tell you.