Undulatus asperatus is a truly unique cloud formation. It is so rare, that it was not categorized as a separate cloud formation, until 2009. Although those clouds’ appearance can predispose you negatively, most times they dissolve quite quickly without causing storms. Like other types of wavy clouds, they are formed when stormy winds and colliding gas masses “whip” the bottom layer of the cloud, creating elegant formations.
The ominous clouds are most often found in the large plains of the United States (such as the state of Iowa) forming ornate patterns, especially in the mornings and afternoons after storms.