The Science of Rainbows: Refraction, Reflection, and Colors

Rainbows are meteorological phenomena that result from sunlight refracting, reflecting, and dispersing in water droplets, producing a spectrum of light in the sky.

Sunlight appears white but is actually a combination of colors. When it enters a raindrop, the different wavelengths of the colors bend at slightly different angles, separating into a spectrum.

As sunlight enters and exits the raindrop, it bends — a process known as refraction. Each color bends differently, leading to their separation into a rainbow's distinct bands.

In the raindrop, the sunlight reflects off the inside surface. This internal reflection is crucial for directing the different colors back out of the droplet at varying angles.

A full rainbow is actually circular. The ground typically obstructs our view, leaving us with the familiar arc. From higher vantage points, like a plane, a full circle can sometimes be seen.

Double rainbows occur when sunlight is reflected twice inside water droplets. The second arc has reversed colors and is fainter. This rare spectacle is a wondrous encore to the primary rainbow.

Your personal viewing angle is key. To see a rainbow, the sun must be behind you, while raindrops are in front. Each observer sees their own particular rainbow due to their unique angle.

Moonbows, or lunar rainbows, occur at night when moonlight refracts, reflects, and disperses in water droplets, creating a faint rainbow.