'UFO' clouds have descended on South Africa, but there's a good explanation

The strangely shaped clouds that appeared over South Africa over the weekend would seem to make the alien movie “District 9” seem all too real.

Viewers took to Instagram to document the strange phenomenon. Take a look:

But there’s a perfectly rational explanation for these “UFO” clouds.

As National Geographic reports, they are known as lenticular clouds, and are typically formed when strong, moist winds move over jagged terrain or mountains, like South Africa’s Table Mountain. As the air passes over this terrain, it cools and condenses into ominous UFO-like shapes, aligned perpendicularly to the direction the air is flowing.

Though sometimes, they can form over flat terrain due to shear winds created by a weather front, according to EarthSky.

These clouds are different from other clouds because they don’t move, according to AccuWeather Meteorologist Jesse Ferrell.

For all these reasons, these clouds are often mistaken for UFOs.

Here are some more clouds. These ones were taken over Ireland in June:

These were spotted over Sierra Nevade in December 2011:

And these ones were seen downwind of Mount Rainier, Washington, in September 2011:

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