July 2, 2013. Evening of July 1, the sky over Syushuanom (Suichuan), Jiangxi, after the rain painted in bright colors.
Unusual clouds, with a slight tinge of green, yellow and red, appeared in the sky. Colorful spectacle attracted passers-by, they stayed to enjoy the incredible skies.
Iridescent clouds — is a relatively rare optical phenomenon. It may be observed at all times of the year, but most often — in the fall.
So when the sun takes a certain position in the sky, while hidden in a fairly dense clouds, any (clear) cloud, located near it, can be painted in the spectral colors. This phenomenon is explained by the fact that the light rays of different wavelengths are deflected in different ways, and hence the light of these waves reaches the observer from different directions.
The cloud can be a rainbow in full or only around the edges, can be dim or very bright colors. In the latter case it is necessary to have clouds of droplets of the same size. Only then it will have a strong color.
Best of all, this phenomenon evident in the high-cumulus (especially on high-cumulus bands) and ice fog clouds.