I found this great photo of mammatus (round puffy) clouds on www.ItWorksForBobbi.com, a site maintained by Canadian blogger, Bobbi-Jo. Per her blog post, her husband captured this photo after they experienced a severe thunderstorm.
Per AccuWeather’s page about mammatus clouds, they state:
Mammatus result from the sinking of moist air into dry air. They are in essence upside-down clouds. The sharp boundary of mammatus is much like the sharp boundary of a rising cumulonimbus cloud before an anvil has formed.
Okay…I just had to do this…
How cool is that? Sometimes turning something upside-down gives us a whole new perspective and understanding.