This incredible cloud formed over Mount Etna earlier this week, spreading out across the Sicilian volcano like a velvety white pancake.
The cloud is altocumulus standing lenticularis, Latin for “lens-shaped.” Lenticular clouds develop in high pressure situations when there are strong winds high up in the atmosphere. The moist air flows over the mountain, cools and condenses into this perfectly pancake-like cloud.
In the most ideal situations, the mountain triggers waves in the air — rising and sinking and rising and sinking. In the areas where the air rises a lenticular cloud will form. The areas where the air sinks will be clear. This can lead to a train of lenticular clouds that extends beyond the mountain.
In other situation, lenticular clouds can form on top of one another like a stack of pancakes. This occurs when there are layers of dry and moist air flowing over the mountain. You can make out that feature in some of these photos.