NOVEMBER 11, 2015 12:30 PM ET // BY DANNY CLEMENS, DSCOVRD
Above: Lenticular clouds over Mount Hotaka in Japan. ALPSDAKE VIA WIKIMEDIA COMMONS Between the UFO that flew over California this weekend and the revelation that the Great Pyramid at Giza may contain a secret passageway, it's been an interesting week.
Now, there's even more fodder for conspiracy theorists: a host of dramatic, alien spaceship-shaped clouds took center stage over Cape Town, South Africa earlier this week:
Did you notice the UFO's flying over #capetown yesterday? 👽 Photo by @mijlof 📷
A photo posted by Instagram South Africa (@instagram_sa) on Nov 8, 2015 at 11:56pm PST Alas, the clouds are not evidence of an impending alien invasion, but rather a perfectly normal meteorological phenomenon. Known to the science community as lenticular clouds, the flying saucer cloud formations are the result of cooling air in the troposphere.
"This type of cloud forms in air that passes over a mountain, rises up again, and cools past the dew point -- so what molecular water carried in the air condenses into droplets," NASA explains. "The layered nature of some lenticular clouds may make them appear, to some, as large alien spaceships."
NEWS: Two-Thirds of the Earth Is Covered by Clouds
Lenticular clouds often form in the vicinity of tall buildings or mountainous terrain, such as the mountains that surround Cape Town. They have, however, been known to pop up occasionally over flat terrain.
The picturesque clouds have been spotted around the world, from South America to Japan.
Much like an alien spaceship on a reconnaissance mission, lenticular clouds can appear and disappear relatively quickly, EarthSky notes.
This story originally appeared on DSCOVRD.