Red and yellow and pink and green—for scientists, a rainbow isn't much of a mystery. Sunlight bounces off raindrops, splitting into its constituent colors and heading backwards at a precise angle, which makes a rainbow appear as a semicircle wherever you stand. But what about two rainbows at once? Now, researchers performing computer simulations think they have an explanation for this odd phenomenon. The key are what the researchers call burgeroids—big raindrops that have been flattened by the buffeting of air. The simulations (pictured) showed that this irregular shape causes the light to bounce off the raindrops at two different angles, producing a colorful, double rainbow in the sky. The researchers hope that their study, which is due to be published later this month in ACM Transactions on Graphics, could make computer graphics more lifelike for use in animated movies and computer games.
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