Undulatus Clouds over Las Campanas ObservatoryExplanation: What's happening with these clouds? While it may seem that these long and thin clouds are pointing toward the top of a hill, and that maybe a world-famous observatory is located there, only part of that is true. In terms of clouds, the formation is a chance superposition of impressively periodic undulating air currents in Earth's lower atmosphere. Undulatus, a type of Asperitas cloud, form at the peaks where the air is cool enough to cause the condensation of opaque water droplets. The wide-angle nature of the panorama creates the illusion that the clouds converge over the hill. In terms of land, there really is a world-famous observatory at the top of that peak: the Carnegie Science's Las Campanas Observatory in the Atacama Desert of Chile. The two telescope domes visible are the 6.5-meter Magellan Telescopes. The featured coincidental vista was a surprise but was captured by the phone of a quick-thinking photographer in late September.
| << Previous APOD | This Day in APOD | Next APOD >> |
The clouds depicted don't fall into the definition of Asperitas found in the 2017 edition of the International Cloud Atlas. In addition, the page of the Cloud Appreciation Society clearly states to not confuse Undulatus with Asperitas: 
