Mammatus clouds are strange and rare.

Have You Seen These Strange Clouds? [Photos]

Strange clouds have been reported over Oklahoma, Nebraska and other states affected by recent strong storms and tornadoes. News station’s social media account have been bombarded with pictures of the strange clouds that look like fingers forming out of the sky. A Slate Magazine writer described them as he saw them, “As they fell, many formed well-defined “heads” at the bottom, like an upside-down mushroom, and had long “stems”. These strange clouds are called mammatus clouds. According to Accuweather, they were coined mammatus clouds because visually, they resemble the bag-like mammary glands — or utters — that hang beneath cows. In order for these strange clouds to form, downward sinking air must be colder than the dry air surrounding it. This cooler air must also have a very high liquid or ice content. These strange clouds usually form on the underside of a cumulonimbus clouds, but they can also develop underneath cirrocumulus, altostratus, altocumulus and stratocumulus clouds. Many bizarre rumors surround these strange clouds, including that they are evidence of the government’s High Frequency Active Auroral Research Program (HAARP) conducting weather experiments, that they are caused by alien vessels or that they are clear indicators of massive tornadoes about to form. Unlike the strange clouds, none of these rumors hold much water. These strange clouds are a naturally occurring phenomenon and are essentially just upside down clouds. Just as a cumulonimbus cloud will rise sharply, the boundary of the mammatus clouds will rise sharply, giving the impression that heavenly fingers are piercing downward. Mammatus clouds sometimes precede violent tornadoes, but usually they follow behind strong storms and indicate, strangely, that the storm has passed.