Why do you get rainbows?

Answer 1

Small droplets of water behave like tiny prisms in the sky. Sometimes the colors will reach our eyes after refracting and undergoing internal reflection. As can be seen in figure 4.3.2, droplets higher in the sky refract red to our eyes while green and blue go overhead. In drops lower in the sky, blue light is refracted and reflected to our eyes, but green and red light bend lower down, missing our eyes. The over-all effect is that we see a primary rainbow- a band in the sky with red at the top and blue at the bottom. Sometimes a less intense secondary rainbow can be seen above a primary one. Light reaches our eyes from a secondary rainbow after two internal reflections inside each rainbow. This has the effect of reversing the colors so the bottom band is red

Answer 2

Rainbows are formed when sunlight is refracted, or bent, through raindrops in the sky. The sunlight is then reflected inside the raindrop and dispersed, creating a spectrum of colors that we see as a rainbow.