Wired reporting on the strange cloud observations. Still figuring out a root cause.
In hill country from Iowa to the Scottish Highlands, sky-gazers have reported some strange, ominous-looking clouds of late. Dubbed undulatus asperatus (turbulent undulation), the atmospheric anomaly could be headed where only 80-odd clouds have gone before: into the International Cloud Atlas. If it makes the cut, asperatus will be the first new addition in more than 50 years.
Where did it come from? Gavin Pretor-Pinney, president of the UK-based Cloud Appreciation Society, has a theory: “It’s warmer, moister air above and colder, drier air below, with an abrupt boundary in between.” Add wind passing over rolling terrain and “you get the same wavy effect as on the surface of water.”