Iridescent clouds are pearly, luminous parts of the cloud .
Observation and Origin
This phenomenon occurs primarily at the edges of clouds that are optically close to the sun (e.g. on altocumulus clouds ). It is created by the diffraction of light rays by water droplets or ice crystals and is one of the events called photometeors .
The edges of the clouds show a purple , blue and green color. Very small water droplets cause iridescence . The small droplets create very large wreaths with wide sections of the same color. Therefore, large areas of the cloud are the same color. The different colors on the iridescent cloud are based on the different droplet sizes. Different sizes of droplets also create different wreaths, so the color is different despite being the same distance from the sun.
- Die Zeit: Das Lexikon Volume 7 , Zeitverlag, ISBN 3-411-17567-2