Rainbows

There is a physics to rainbows. A rainbow happens When light meets an interface between air and water some of it is reflected and some of it passes through. The angle of refraction depends both on the light’s wavelength and on the angle at which it hits the surface. Wavelength corresponds to color, so the colors separate into the familiar bands, which creates the color. 

Local changes in the rain shower can affect the mirror rainbow completely differently from the direct-view rainbow. The Size of the rain drop contribute at the base, whereas near the top, light from the large. Larger raindrops are squished flatter on the underside by air resistance as they fall and usually make up a small fraction of a rain shower. Our understanding of rainbows is very robust now, but not complete. There are undoubtedly details that can still be improved.