Look at this strange feather-like iridescent cloud photographed in the sky of Warwick, Australia on March 28, 2016.
The rainbow cirrus cloud also known as “feather clouds” or “mares tails” really looks like a feather floating in the evening sky.
Cloud iridescence is the occurrence of colors in a cloud. It is a fairly uncommon phenomenon, most often observed in altocumulus, cirrocumulus, lenticular clouds and cirrus clouds.
Iridescence is generally produced near the sun. Iridescent clouds are a diffraction phenomenon caused by small water droplets or small ice crystals individually scattering light. Larger ice crystals produce halos.
If parts of clouds have small droplets or crystals of similar size, their cumulative effect is seen as colors. The cloud must be optically thin, so that most rays encounter only a single droplet. Iridescence is therefore mostly seen at cloud edges or in semi-transparent clouds, and newly forming clouds produce the brightest and most colorful iridescence.
In our case, the feather-like cirrus cloud photographed by Kerri Trusz, commonly found of altitudes of 20,000 feet (6,455 m) or higher, was most probably composed of hexagonal ice crystals.
