Also called: Mother-of-Pearl Clouds, Wave Clouds, or Polar Stratospheric Clouds (PSCs)
A southern girl like me has only seen these clouds in photographs. But the photos are breathtaking. They look like iridescent sheets, undulating with the winds and waves of the atmosphere.
They hang out in the lower stratosphere, 9 - 16 miles high and can be seen in winter, just after sunset and just before dawn. These clouds consist of ice crystals that are uniform in shape and size. The unusual colors result when the sun’s rays hit the thin clouds at just the right angle.
These are regarded as “dangerous beauties” by scientist who believe they are helping destroy the ozone layer. In August 2006, an unusual cloud formation was spotted over Australian Mawson Station in Antartica (see inset NASA photo). It was believed that this unusual sighting was caused by extreme weather conditions.
In January 2008, nacreous clouds put on a gorgeous month-long display in Scandinavia (you can read about it in detail and see some amazing photos on this page).
Whatever your genre, these mysterious and beautiful cloud formations could add depth and color to your composition.