I took a course on weather last year. The professor was a PhD climatologist from a major university who knew his subject very well. He gave me the impression that he was an expert on climate change phenomena and had an enviable ability for clarity of explanation of complicated subjects.
Along about 6 weeks into an 8 week course, he explained how rainbows work. His explanation was astonishingly clear and intuitive for someone who knows basic optics and understands refraction of light.
At the end of the relatively lengthy presentation, complete with computer projection onto a large screen before about 25 people, he added words to the effect, "We're not sure why there were no rainbows before the flood. I guess some things we will never know."
The class erupted in nervous giggles, until, "Well, that's what the Bible tells us, that the first rainbow was after the flood," and a hush fell over the group as we all realized in unison that he was not joking.