Think you know all there is to know about rainbows? Our friends at Big Bang Blogs give us the lowdown on the weirdest rainbows out there.
Upside down rainbows
Upside down rainbows, or ‘circumzenithal arcs’, to give them the proper name, are not caused by rain. Normal rainbows form when light refracts through raindrops, mist, or sometimes even sea spray. The upside down kind however, are caused by ice crystals in the air. They are more common in cold climates, but still fairly rare.
Double rainbows occur when the sunlight is reflected twice inside the raindrops. The second rainbow usually sits outside the first, and looks dimmer and more blurry than the original. Because of the angle of reflection, the second rainbow appears with the opposite colour scheme to the first.
It sounds complicated, but really a supernumerary rainbow is one with smaller repeating rainbows inside it. The smaller rainbows tend not to have the same colour patterns as a normal rainbow, and the colours are lighter.
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