Cirrocumulus Lacunosus Cloud

July 11, 2017

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Photographer: Bertrand Kulik
Summary Authors: Bertrand Kulik; Jim Foster

The photo above shows an unusual cloud formation high above Paris, France, as observed in the early afternoon of May 14, 2017. This is evidently a cirrocumulus lacunosus cloud (full of holes in Latin). Its honeycomb nature can be more easily seen in the close-up at left. Though lacunosus type clouds can occur at different heights in the atmosphere, they're more frequently viewed as a form of cirrus. Composed of water droplets at low and mid altitudes and of ice crystals above about 22,000 ft (6706 m), they tend to be quite short-lived. It's believed that lacunosus take shape when a cooler layer of air in the atmosphere pushes through a warmer layer. As the cooler air sinks the holes are formed, and as the warmer air rises, replacing the cooler air, ruffles form around the holes.

Photo Details: Top - Camera Maker: Camera Model: Canon EOS 5D Mark III; Lens: TAMRON SP 15-30mm F/2.8 Di VC USD A012; Focal Length: 15.0mm; Aperture: ƒ/5.6; Exposure Time: 0.0008 s (1/1250); Software: Adobe Photoshop CC 2015 (Windows). Botttom - same except: Focal Length: 27.0mm; Aperture: ƒ/16.0; Exposure Time: 0.0063 s (1/160).