Make Your Own Rainbow

HAVE you ever made your own rainbow? Have you ever sprayed water through the air on a sunny day and suddenly thrilled to your own miniature rainbow? If not, no doubt you have been stopped in your tracks when someone exclaimed, “Look! A rainbow!” That beautiful arch of colors never ceases to amaze us. But what exactly is a rainbow? How is it formed?

There are three basic prerequisites if you are to see a rainbow​—the sun behind you and no higher than 40 degrees above the horizon, and a rain shower ahead of you. If conditions are ideal, you will actually see two rainbows​—an inner one with stronger colors and an outer one that might look washed out. And how many colors will you see? Technically, there are seven colors​—violet, indigo, blue, green, yellow, orange, and red—​although some experts discount indigo. Most people perceive only four or five because of some blending.

But what makes the colors? The raindrops break up the sunlight into colors by acting like tiny prisms and mirrors, thus transmitting colored light to the eyes. Each rainbow is unique to each observer. Why is that? Because difference of observer position will mean difference of angle between the raindrops and the sun’s rays. Furthermore, each person is viewing different sets of raindrops. So when you admire the beauty of a rainbow, you are seeing something unique​—your particular rainbow.