photo #9369636

As Sandy Cimbaro (Cloud Appreciation Society Member 48,460) was flying into Seattle, Washington, US, her plane passed through a shower cloud. Beams of sunlight dodged the patchy clouds, illuminating select segments of the rain sheets. Fragments of primary and secondary rainbows appeared as these shafts of sunlight were reflected and refracted within the raindrops. Though we can’t see the position of the Sun in Sandy’s image, two clues from these rainbows tell us it was right down near the horizon.The first clue is in the angle of the bows. The arcs of rainbows are always centred on the antisolar point, which, from Sandy’s perspective, is in the exact opposite direction from the Sun. Sandy’s bows are centred on a point not far below the horizon, so the Sun behind her must have been only just above it. The second clue that the Sun was low in the sky comes from the colours of the rainbows – or, rather, the lack of them. The bows show no blues and greens, and that’s because they were formed by the golden evening rays of the setting Sun. These colours had been largely filtered from the sunlight during its long passage through the low atmosphere, and so they were missing from the rainbows it formed. ‘Cabin crew, please prepare for landing.’