Have you seen these photos getting passed around on social media? I originally saw them when they were shared by Meteorologist Shel Winkley from KBTX in Bryan, TX. He shared the photos after viewers in his area spotted the funky looking clouds. Photo credit goes to M. Davis.
They look pretty cool, right? The initial thought most people have when seeing this kind of cloud is that it's some sort of alien UFO! Actually, it's a lenticular cloud, and an impressive one at that. According to the dictionary, "lenticular" means to be shaped convex on both sides, kind of like a contact lens. This is appropriate, given that's exactly how lenticular clouds are shaped. They also can have many layers (like this one does). In my opinion they look a bit like crepes (thin, french pancakes) stacked one on top of the other.
(Photo from taste.com/au)
Have I made you hungry yet?
Let's get back to the topic. How exactly do lenticular clouds form, and why do they look the way they do? Well, it usually has to do with topography. In many cases lenticular clouds form near ranges of mountains or hills. As air flows towards a mountain, it is forced upward and over it.
Now imagine that the air that's flowing over the mountain has a good bit of moisture to it. As the air rises it gets cooler and cooler, forcing the moisture in the air to condense and create a cloud! In a lot of situations, this will happen right at the top of the mountain, creating a kind of lenticular cloud mountain-hat.
(Photo by Dennis Stilwell of nwhiker.com)
In other situations, areas of lenticular clouds will form well after the air has rolled over the mountain. Basically, the air will rise over the top of the mountain and then start to descend. This action of rising and falling then repeats itself as the air continues to flow on its merry way, even after there is no mountain for the air to move over. It's a kind of wave that happens in the sky, with the clouds forming at the peak of each wave crest. I tried to draw this out to represent what's going on, but keep in mind- I'm a meteorologist, not an artist!
What's intriguing about this particular viral photo example is that there was no mountain range or no city with tall buildings (which act like man made mountains) nearby. So how can lenticular clouds form without the rolling topography?
This question has led to a few different answers from meteorologists who have discussed it. The first thought is that perhaps they were blown downwind from where the clouds originated. This happens frequently, but likely was not the case in this situation. They would have had to have been blown very far, and wouldn't have maintained their structure. What I think is more likely is that the flowing air encountered a rain shower or thunderstorm and flowed up and over it, creating that similar wave structure to as if a mountain had been there instead. If that's the case, it's a pretty rare circumstance!
Now you know the story behind the viral photo!
Meteorologist Julia Weiden