Double rainbows happen when light reflects twice inside each droplet, reversing the color order.

The longer version

Light can bounce twice inside a raindrop before leaving, and each internal reflection costs some brightness. The second bow therefore appears fainter and sits higher in the sky, with its colors running in the opposite order because the extra reflection flips the sequence.

Between the two arcs the sky is noticeably darker, a band sometimes called Alexander's dark band after the ancient commentator who described it. Supernumerary arcs, thin pastel fringes just inside the main bow, come from wave interference rather than simple geometry. Triple bows have been photographed, though they are very hard to spot.

Where this entry sits

These facts explore how light behaves and how human eyes turn it into the colors we see. Along the way you meet rainbows, prisms, mirrors, shadows, lasers, and optical tricks that fool our vision every day. The full list sits on the Color and Light page, where every entry is listed in order.

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More From Color and Light

Eight more entries

You never see a rainbow from directly overhead because the geometry requires looking away from the sun.

Red light bends least through glass, while violet light bends the most.

The color orange takes its name from the fruit, which had the word first.

Purple and violet describe similar hues, though violet refers to a single wavelength of light.

Many languages have fewer basic color words than English, sometimes grouping blue and green together.

Turquoise sits between blue and green on the spectrum and is named after a gemstone.

Gold and silver describe metallic surface appearances rather than one particular wavelength of light.

The color of a flame changes with temperature, shifting from red toward blue as it gets hotter.

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