Rainbows form when sunlight interacts with water droplets in the atmosphere.
When
light enters a raindrop, it bends (refracts), reflects off the inside surface of
the droplet, and then bends again as it exits. This process separates the light
into its component colors: red, orange, yellow, green, blue, indigo, and violet.
Each color emerges at a slightly different angle, creating a circular arc of color
in the sky. The observer must be positioned with their back to the sun and rain in
front of them to see a rainbow. While most people see only part of the arc,
rainbows are actually full circles—though the ground typically blocks the bottom
half from view. Double rainbows occur when light reflects twice inside the droplet,
producing a fainter, reversed arc. Rainbows have fascinated humans for centuries
and appear in many myths and artworks. Scientifically, they remind us of the beauty
of light and water in nature.