Asperitas Clouds Over Paris

April 03, 2017

Undulatus_Paris_2 (8)

April 2017 Viewers' ChoicePhotographer: Bertrand Kulik
Summary Authors: Bertrand Kulik; Jim Foster

Shown above is an eye-catching deck of asperitas clouds (formerly known as undulatus asperatus) observed over Paris during the morning of March 29, 2017. Their grim appearance adds a gloomy note to the emergence of spring in the City of Light. These clouds have a predisposition to form over relatively featureless terrain following a period of particularly stormy weather, sometimes only a few hours after severe storms have departed. The formation of these rarely seen clouds is evidently related to gravity waves generated by the severe weather that, because of strong shear, dramatically alters the aspect of mid-level cloud layers. For reasons that are unknown, they're more often reported before noon than during the late afternoon hours.

Photo Details: Camera Model: Canon EOS 5D Mark III; Lens: TAMRON SP 15-30mm F/2.8 Di VC USD A012; Focal Length: 28.0mm; Aperture: ƒ/11.0; Exposure Time: 0.010 s (1/100); ISO equiv: 100; Software: Adobe Photoshop CC 2015 (Windows).