Nacreous Clouds Over Norfolk England

February 16, 2016

Photographer: Kate Cudden
Summary Authors: Kate Cudden; Jim Foster
Shown above is an eye-catching display of nacreous clouds observed at sunset above Norfolk, England. These extremely cold, high altitude clouds, also referred to as polar stratospheric clouds or Mother of Pearl Clouds, are likely composed of nitric acid and traces of water vapor. They most often form during the winter season in low-mid levels of the stratosphere, but usually at altitudes below about 15 miles (24 km). The coloration of nacreous clouds is attributed to diffraction of sunlight by minute ice crystals of about the same size (approximately 0.0004 in or 0.01 mm in diameter). Click here to see an animation of this display filmed by Sam Cornwell near his home of Scottish Borders, U.K. Photo and video taken on February 2, 2016.
Photo Details: Camera Model: Canon EOS 40D; Exposure Time: 0.004 second; Lens F-Number: ƒ/10; ISO Speed Ratings: 200; Shutter Speed: 1/250 second; Focal Length: 18 mm.