The one thing these images do not convey is the sense of motion that occurs with these systems. In the span of only a few minutes the lobes of these mammatus will shift and change. This gives the atmosphere a feeling that it is "boiling" in advance of potentially "apocalyptic" storms.
Click in any of the images to see it in the original gallery.
I hope you avoided this week's nasty weather and can enjoy these images from the safety your computer!