Iridescent Clouds over Sweden

Iridescent Clouds over Sweden

Image Credit:
Goran Strand

Explanation:
Why are these clouds multi-colored?

A relatively rare phenomenon in clouds known as
iridescence can bring up unusual colors vividly —
or even a whole spectrum of colors simultaneously.

These polar stratospheric clouds
also,
known as
nacreous and mother-of-pearl clouds,
are formed of small
water
droplets of nearly uniform size.

When the Sun is in the
right position and, typically, hidden from direct view,
these
thin clouds can be seen significantly
diffracting sunlight in a nearly coherent manner, with
different colors
being deflected by different amounts.

Therefore,
different colors
will come to the observer from slightly
different directions.

Many clouds start with uniform regions that could show
iridescence but
quickly become too thick, too mixed,
or too angularly far from the
Sun to exhibit striking colors.

The featured image and an
accompanying video were taken
late in 2019 over
Ostersund,
Sweden.