What causes a rainbow?: Quick Facts

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Photos

A bright rainbow arcs over gentle waves at Karon Beach in Phuket, Thailand, with blue sky and scattered clouds above the calm sea.

$Diagram showing sunlight entering a water droplet, refracting, reflecting inside it, and emerging as separated red-to-violet light. Rays reaching an observer at about 42 degrees for red and 40 degrees for violet form a rainbow opposite the sun.$

A double rainbow arcs across a cloudy sky above a grassy meadow or field in the countryside.

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Topics

light raindrop rainbow Why are rainbows curved?colour blue light Sunlight photon luminous intensity How Is Light Both a Particle and a Wave?speed of light brightness