Environment Planet Earth Rare 'Fluid' Sunset Reveals Unique Clouds By Michael d'Estries Writer State University of New York at Geneseo Michael d’Estries has been writing about science, culture, space and sustainability since 2005. His writing has appeared on Business Insider, CNN, and Forbes. our editorial process Michael d'Estries Updated June 07, 2017 This rare undulatus asperatus sunset was captured on June 2nd over North Dakota. . (Photo: Mike Olbinski) Share Twitter Pinterest Email Environment Weather Outdoors Conservation We've all gazed in awe at the beauty of a sunset, but what storm-chaser Mike Olbinski captured recently is something else altogether. "We were chasing northeast of Bismarck, North Dakota, and as storms were dying out, we decided to go for a lone cell on the backside of a line of storms," he wrote on YouTube. "We knew it had a hail core on it and we were hoping that we might get some nice sunset color at least on the storm as it moved past us, and hopefully some lightning bolts. But we had no idea what we were about to encounter. The clouds were taking on a very different, curvy, wave-like appearance and suddenly we knew what we were seeing." What Olbinski and his team witnessed was a rare formation of "undulatus asperatus." Like something out of a Hollywood movie with an apocalyptic bent, these clouds are often low-lying, wavy, fluid and dramatically illuminated. As Olbinski and his team captured in a time-lapse, the beauty of these unique clouds is particularly enhanced at sunset. In March 2017, the World Meteorological Organization formally recognized undulatus asperatus as a new category of cloud in its International Cloud Atlas — the first such addition in over half a century. "A formation made up of well-defined, wavelike structures in the underside of the cloud, more chaotic and with less horizontal organization than undulatus," the formal definition reads. It is characterized by localized waves in the cloud base, either smooth or dappled with smaller features, sometimes descending into sharp points, as if viewing a roughened sea surface from below." Another, more apocalyptic example of undulatus asperatus can be seen below: As for Olbinski, he says this particular sunset will stick with him for some time to come. "This was undoubtedly one of the most incredible scenes I've witnessed chasing storms for the past eight years," he added.