You may be looking at the photo above and be thinking, "Is that the apocalypse?" or at the very least, "Wow, that looks really eerie," but rest assured that we aren't in the midst of facing our impending doom of death by apocalypse...yet. What you're seeing in the photo is actually a weather phenomenon that I'm obsessed with called mammatus clouds. And yes, they're named after boobies (mammary glands).
These protruding round structures, usually compared to popcorn and cotton balls, are most commonly found on the underside of larger parent clouds in severe thunderstorms, but can sometimes be found underneath cirrus and stratocumulus clouds as well.
It is not for certain how these cute little cloud balls form, however a number of theories have been developed about the development process of mammatus clouds. One such theory is that the mammtus clouds are formed when ice crystals fall out of the cumulonimbus cloud's anvil. The ice crystals sublimate, or change from ice to water vapor as they fall, causing the surrounding air to thermodynamically cool. The cooled air then becomes "negatively bouyant" and begins to sink, producing the punched-out look indicative of mammatus clouds.
So next time you're sky watching after a thunderstorm be sure to look up and around for these amazing little clouds, and be amazed by their eerie beauty.