Reflect and refract
When was the last time you looked out the window and said, “Oh look! There’s a many-coloured refraction of light from drops of water!”? Well – OK, if you said that last week then feel free to skip the next paragraph, but most of us refer to the sudden splash of colours in the sky as a rainbow, an eye-catching natural phenomenon which has been rich in cultural significance throughout human history.
The science behind rainbows is reasonably straightforward: when sunlight hits a raindrop, it slows down and is refracted, or made to change direction. The raindrop acts as a tiny prism, splitting the white light into all its individual hues. Some of this light is reflected back and further refracted on entering the air again, dispersing outwards to create the spectrum of shades whose names we probably all remember from the school playground.