Nacreous Clouds Over Switzerland

February 16, 2015


Photographer: Verena Tiessen
Summary Authors: Verena Tiessen; Jim Foster
 February 2015 Viewer's Choice
The photo above showing magnificently colored nacreous clouds was taken from Rafz, Switzerland on January 1, 2015. These high altitude, and generally high latitude, wave clouds form from gravity waves and tend to occur on the lee side of mountain ranges. In polar regions nacreous clouds can play a role in the depletion of stratospheric ozone. Similarly sized, minute ice crystals (likely no more than 0.0004 in or 0.01 mm in diameter) are responsible for their iridescent colors. Nacreous clouds are infrequently observed in the mid-latitudes.
Photo details: Camera Model: NIKON D600; Lens: 28.0-300.0 mm f/3.5-5.6; Focal Length: 210mm (35mm equivalent: 210mm); Aperture: ƒ/18.0; Exposure Time: 0.0008 s (1/1250); ISO equiv: 320; Software: Adobe Photoshop CS6 (Windows).