Science of the Rainbow

The spectrum depends upon light of different colours being slowed by different amounts: the refractive index of a given substance, say glass or water, is greater for blue light than for red. You could think of blue light as being a slower swimmer than red, getting tangled up in the undergrowth of atoms in glass or water because of its short wavelength. Light of all colours gets less tangled up among the sparser atoms of air, but blue still travels more slowly than red. In a vacuum, where ther...

 How a Rainbow Works

If you want to see a rainbow you ' have to have the sun behind you when you look at a rainstorm. Each raindrop is more like a little ball than a prism, and light behaves differently when it Sits a ball from how it behaves when it hits a prism. The difference is that the far side of I raindrop acts as a tiny mirror. And that is /hy you need the sun behind you if you want 0 see a rainbow. The light from the sun turns somersault inside every raindrop and is reflected backwards and downwards, wh...