can anyone tell me what this is ?

After seeing a video I agree with words of "jketcham", these are Cb mammatus with undulatus forms. Definatelly something "new".
I guess a bit later it started to rain? Because I remember such intense (Sc) undulatus forms few days ago here, they appeared just before the rain came.
As I can see you were under a huge MCS, Cb clouds involved as well. So maybe mammatus swept so low, that then also undulatus forms appeared. Also height is right even for Sc class.
But for my opinion that cannot be a lenticularis form, even you ignore undulations :? Sc len are different.

Its cool...thats what it is!

I did a ctrl +A on the photo and saw the invisible watermark too!

© BIG GUY UPSTAIRS :lol: Joey, did you get His permission? lol
Its cool...thats what it is!

I did a ctrl +A on the photo and saw the invisible watermark too!

© BIG GUY UPSTAIRS :lol: Joey, did you get His permission? lol

LOL. Ya, no worries.. permission was granted to let me post them...

Actually, the cool thing is I didn't have my camera with me when it occured, so I was upset I missed it and when I got home from work I got this email from Wayne that lives here in town that had the pictures attached, he was awesome for letting me post them!

The other two taken by Amber, I actually work with her and didn't know she had taken any until the next day... both Amber and Wayne were awesome for letting me post those!
Awesome display of atmospheric wonder. Sure wish I could of seen it first hand.
Guys are you sure this is not a digital effect? I would not bet on it....
The definition is too much perfect...mmm

These pics are very much real! I live in Pittsburg, KS, a town that they passed over, saw them with my own eyes! It was a very spectacular event! I've never seen such a thing.

Wow then I belive you: amazing nature :wink:
Originally posted by Jeff Snyder
Therefore, my hunch is that the clouds being discussed are occurring atop a very deep cold pool -- the density difference between the warm cloud-layer and the cold (stable) sub-cloud layer may be likened to the density difference betweeen the water and air (obviously, the magnitude of difference in the former is considerably less than the latter).
I think this is a good possibility. As I alluded to above, these clouds were shot at 9-9:30am. The satellite image in the somethingawful forum was a 0900Z image, so extrapolating, one would think that the Joplin area was well worked over, airmass-wise. So I defintely can theorize about a cold sub-cloud layer.
When in them gravity waves.

These are definitely surface gravity waves on the interface of fluids with different densities. Mammatus are usually associated with subsidence pockets at higher levels. These appear to be a lower level feature with undulating motions (both upward and downward) on the upper interface of a cold pool as Jeff mentioned.

Incredible pictures.
They remind me of clouds that I've seen at the beginning of a spring severe weather day. Warm front-elevated convection moves out in the morning. Then afternoon and evening, the surface based boomers move in, if the cap don't block'em.

I also like everyone calling them year-2005 clouds from the other thread, though I've seen them other years.