Amersfoort Iridescence

February 28, 2005


Provided by: Jurgen de Boer
Summary authors & editors: Jurgen de Boer

On the 21st of January (2205), from Amersfoort, Netherlands, I was treated to a beautiful display of cloud iridescence. Irisation or iridescence is caused by diffraction of light by uniform cloud droplets or on occasion, ice crystals. Iridescence is a remnant of very large coronal diffraction rings around either the Moon or the Sun -- much distorted and incomplete. Often the iridescence looks like an oily water surface with pink and light green pastels appearing most prominent. Cloud types which often show iridescence are altocumulus lenticularis, cirrocumulus and occasionally fractocumulus.

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