© Roberto Antezana
This eerie iridescent cloud appeared over Santiago de Chile at sunset on July 15, 2016.
This is one of the most unbelievable rainbow cloud I have ever seen in my life!
Cloud iridescence is a fairly uncommon phenomenon when colors appear in a cloud, most often altocumulus, cirrocumulus, lenticular clouds and cirrus clouds.
© Roberto Antezana
Iridescent clouds are a diffraction phenomenon caused by small water droplets or small ice crystals individually scattering light.
The colors are usually pastel, but, as in these pictures, they can be very vivid. Newly forming clouds produce the brightest and most colorful iridescence.
© Roberto Antezana
Iridescence is generally produced near where the sun appears in the sky, with the sun's glare masking it, so it is more easily seen by hiding the sun behind a tree or building. In our case, it was hidden by the Andes. Other aids are dark glasses, or observing the sky reflected in a convex mirror or in a pool of water. Or one can simply block the sun (but not the cloud) with the palm of one's hand.
A few days before, this blood red sunset sky engulfed the smoggy sky of Santiago de Chile.
© Roberto Antezana
© Roberto Antezana
These pictures are almost scary! as if we were playing with our atmosphere, with the clouds in the sky.
Comment: Though beautiful, these clouds may be an indication of the cooling atmosphere caused by ice crystals. Impending ice age, anyone?
What causes iridescent clouds?
with the atmosphere.