How do they form and why do they have a strange shape?
First of all there name comes from the Latin word for ‘breast or udder’ but to me they look like bubbles all over the sky…they are in fact upside down clouds and form on the bottom of massive cumulonimbus clouds.
The theory is, that they usually form where very warm and very cool air both meet, different atmospheric conditions produce different mammatus clouds, they can look smooth, jagged, translucent or opaque depending upon the conditions…but no matter what, they look very impressive in the sky, take your pictures and enjoy them, then quickly take cover as they are very unpredictable and you most probably will get wet!!!
Wikipedia has more information on these rare cloud formations at:
Please go to the NOAA (National Oceanic and Atmospheric Administration) website where you can find out a lots of information about the different types of clouds in the sky at: