Double Rainbow consists of a bottom — brighter, and above, less bright, for a short period. The first is called primary, the second — sideline. Multiple rainbows
Multiple rainbows
Admiring the rainbow we sometimes notice that it has a twin – another arc, modest, slightly prominent. And some have seen just three or four rainbows at the same time. But such cases are very rare. Double Rainbow consists of a bottom – brighter, and above, less bright, for a short period. The first is called primary, the second – sideline. Both rainbows face each other with red edges of the arc so that the main rainbow red edge was on the convex side. Secondary rainbows are caused by a double reflection of sunlight inside the raindrops, and appear at an angle of 50–53°. As a result of the second reflection, the colors of a secondary rainbow are inverted compared to the primary bow, with blue on the outside and red on the inside. The secondary rainbow is fainter than the primary because more light escapes from two reflections compared to one and because the rainbow itself is spread over a greater area of the sky. The dark area of unlit sky lying between the primary and secondary bows is called Alexander’s band, after Alexander of Aphrodisias who first described it.
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