Aconcagua Iridescence ~ At 6960m high, Aconcagua is the highest peak of the Andes. Radek Grochowski shot these images on 18th February ‘12 from Plaza de Mulas at 4400m looking towards the summit region. “The wind was heavy and the summit was surrounded by a bizarre veil of clouds which were changing their shape rapidly. Bright iridescence was present most of the time. What's on the photos is probably the most vivid and beautiful iridescence I have ever seen.  Nikon D300 and Nikkor 18-200 lens.” Images ©Radek Grochowski, shown with permission
Diffraction of sunlight by individual cloud droplets produces the iridescence. The colours are most vivid when the cloud has freshly formed and the droplets are all of similar size. These cloud veils induced by the airflow over the mass of Aconcagua are ideal.

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Wind and cloud drive up the mountain slopes.

The colour intensities are as Radek saw the scene. Iridescence is notoriously difficult to reproduce faithfully in images and too many have their saturation 'Photoshopped' to an unnatural degree. These images have only been very slightly and thoughtfully enhanced to reflect accurately the visual appearance.