Iridescent Clouds and Irisation

Photo copyright by Craig Johnson in Cedar Falls, Iowa on November 8, 2022.

Iridescent clouds are clouds of ice-particles. They display brilliant spots or borders with red and green colors. The colors are seen 30 degrees or less from the Sun. The ice particles are very small and are nearly all of the same size. Irisation, which is the coloration seen at the cloud edges, are mostly red in this photo but there are hints of green tinges too. The clouds displaying the irisation are Altocumulus with a distinct pattern caused by wavy motion in the wind.