February - halos You are here: Home Photo gallery Atmospheric optics Light in water droplets Cloud bow

A bow like the rainbow, formed in cloud droplets. As cloud droplets are much smaller than raindrops, the spectral colors of the white light have a much larger range of exit angles from a droplet, and as a result, the colors overlap so a white bow is produced. The cloud bow is often visible from an airplane flying over a sunlit cloud deck. Sometimes, especially during sunrise or sunset, the cloud bow is visible to an earth-bound observer. It may then appear in altocumulus or stratocumulus clouds on which the sun shines from below and on the edges. With low sun elevations, the cloud bow is usually colored red, because the sunlight is reddened by atmospheric scattering.

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