The Colours of Iridescent Clouds


Iridescent Clouds at White Sands #3

High clouds shimmer with iridescent colours near the Sun in an unusual display of atmospheric optics.

As I was getting ready to shoot the sunset at White Sands National Monument last evening, December 10, I looked up at the late afternoon Sun and saw it embedded in thin clouds tinted with iridescent colours. My dark sunglasses helped me see the phenomenon by eye, and underexposing the image helped me capture the colours by camera.

The effect is more common than you might think, but being so close to the blinding Sun iridescent clouds often go unnoticed. The almost metallic-looking colours are caused by clouds made of water droplets of such a uniform size they diffract the sunlight and spread the white light into a stunning range of colours.

Iridescent Clouds at White Sands #1

This image frames the scene in portrait mode. I took several images over the few minutes the effect lasted. But the clouds soon moved off or changed structure and the iridescence faded. Despite the Sun shining through similar looking thin clouds the next evening, December 11, I saw no such iridescence.

For more information see Les Cowley’s excellent page at his Atmospheric Optics website.

It’s just another example of the wonderful phenomena of light and colour that the sky can present to the watchful.

– Alan, December 11, 2013 / © 2013 Alan Dyer

 

Sunset at White Sands


Sunset at White Sands, New Mexico (Dec 10, 2013)

The setting Sun sets the sky on fire above the gypsum dunes of White Sands National Monument.

A week ago I was at Chiricahua National Monument in Arizona for the sunset. This was the scene tonight, at White Sands National Monument in New Mexico.

I was on top of a sand dune at the Yucca picnic area on the Loop Road, watching an amazing sunset over the dunes. The clouds lit up on cue and Venus began to appear, visible here left of centre. The horizon was rimmed with a rainbow of twilight tints.

It was a cool evening, and driving on the unpaved Loop Road graded out of the white sand made me feel I was back home driving on a snow-covered back road. But the white stuff wasn’t snow but pure white gypsum.

This image is a High Dynamic Range (HDR) stack of seven exposures taken at 2/3rd stop increments and composited with Photomatix Pro. The technique brings out details in the shadowy landscape while preserving the bright sky. I used the 14mm Rokinon lens on the Canon 5D MkII. Final processing was in Photoshop CC.

– Alan, December 10, 2013 / © 2013 Alan Dyer