Mammatus Clouds Over Pittsburgh

Tonight it seemed, from the pictures that people in different parts of the city were posting on social media, that the entire city was covered by these unique looking "Mammatus clouds."

Mammatus derives from the Latin word mamma, which means breast. William Clement May, an English meteorologist who studied clouds, created this term. You can see from the picture how the clouds resemble breasts, or pouches.

Apparently, these "pouches" form by cold air that sinks downward from the highest cloud in a thunderstorm. We didn't have a thunderstorm on this night, so I wonder whether there was a nearby storm somewhere else in the city, or if there is another way that these clouds form. Most Internet resources seem to have an idea of how these clouds are formed, but also acknowledge that much about them is still a topic of ongoing research.

The pictures below are so cool. I didn't use any filters! These clouds were passing above my house at the same time as sunset, which made for some really unique and beautiful scenes.