A double rainbow happens when sunlight is reflected twice inside raindrops instead of just once, splitting and sending the light back to you at two different angles so you see two colored arcs in the sky.

Quick Scoop: What causes a double rainbow?

  • Sunlight enters round raindrops and bends (refraction), then reflects off the back of the drop and bends again as it exits, creating the main rainbow.
  • For a double rainbow, some of that light bounces around twice inside the same drop before leaving, which sends it out at a slightly different angle and makes a second, fainter arc above the first.
  • That second arc is dimmer because each extra reflection wastes light, so less brightness reaches your eyes.
  • The colors in the second rainbow look reversed: red is on the inside and violet on the outside, thanks to the extra internal reflection flipping the order.
  • Both arcs appear when the Sun is behind you, rain is in front of you, and the drops are the right size (typically larger raindrops after a shower, often near sunrise or sunset when the Sun is low).

In simple terms: one set of light rays “takes the short route” and makes the bright main rainbow, while another set “takes an extra lap” inside the drops and paints a second, softer rainbow with its colors flipped.

TL;DR: A double rainbow is just sunlight doing an extra internal bounce inside raindrops, creating a second, fainter arc with reversed colors above the main rainbow.

Information gathered from public forums or data available on the internet and portrayed here.