Reflections on Rainbows
The previous OPOD-Atoptics Highlight showed a puzzling coloured spot - a fragment of a 'reflection rainbow'. Here we see these bows in their full glory plus ones from more complex reflections. William Bradley saw them in Northern Ireland.?
Ordinary rainbows (are they ever just ordinary) come from reflections inside raindrops. One for a primary bow, two for a secondary, yet more for higher order bows.
The extra above-horizon bows pictured above are generated by sunlight first reflected from the calm river surface. The upward going reflected sunlight produces 'reflection bows' centred on a point at the same altitude as the sun but directly opposite.
Reflected bows appear in the water. Rays from raindrops that would otherwise form the above-horizon rainbow reflect from the water. Confusingly, they form continuations of the above horizon reflection bows.
One external reflection is not enough for 'reflected-reflection' bows. Sunlight reflects off the river before reaching a raindrop. The outgoing rainbow light reflects once again from the water. These bows form below-horizon continuations of the 'ordinary' rainbows.