photo #9357724

A low cloud like this Cumulus looks solid because its abundant tiny water droplets scatter sunlight this way and that. As a result, much less light passes through a Cumulus cloud than through a high, translucent ice-crystal cloud like Cirrus, which is generally thinner with fewer, larger ice crystals along our line of sight. The scattering of light by all the Cumulus cloud’s droplets makes it appear brilliant white on the side illuminated by direct sunlight and shaded on the side away from the Sun. This is why Cumulus is described as being optically thick. It may be the happy-go-lucky fair-weather cloud, but every little Cumulus has its dark side.Cumulus mediocris in front of the Sun, with a backdrop of Stratocumulus, Altocumulus, and Cirrus, spotted over Northamptonshire, England by Lucy Allen-Shirtcliffe (Member 52,456).