Clouds generally have flat bottoms because the layer or boundary at which water condenses in the atmosphere is usually smooth and uniform. However, if this boundary is turbulent and mixed the cloud layer reflects this in its shape. Here well-rounded Mammatus clouds have formed on the outskirts of a thundercloud. Should these types of clouds be illuminated when the sun is low in sky, as they are here, the bias relief and colors of the clouds can be striking. Be weary of the of the weather if these clouds are seen in the sky.
Storm passed through here last night, nothing much really came from it. Spotty thunderstorms at best, but there for sure was potential for more than what we received. This clumpy clouds contribution photo from swc was taken from his back yard as the storm was rolling through the Twin Cities.