Natural phenomena: Fire rainbow


These colorful offshoots can often be seen during the summers of middle-latitude areas, such as most of the United States. What they actually are is a large halo of refracted light, and despite their nickname, they have nothing to do with either fire or rainbows. They only occur when the sun is at least 58 degrees above the horizon, when there are cirrus clouds in the sky that are filled with plate-shaped ice crystals. The refraction of light is always parallel to the horizon, and because the arcs are so big, only sections of them are ever commonly seen—which is why it can look like certain patches of cloud are on fire (or throwing a rave). The proper name for these things, in case you ever need to impress a scientist, is ‘circumhorizontal arc.’



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