What are these clouds?

I have took these pictures last years. It's the first time in my life I was seeing that kind of cloud and I never see it again since then.

And I don't have found other similar pictures on the net.

So, is there someone here who can tell me what are these "jellyfish looking" clouds? And tell me how it forms??!





They look like "Stratocumulus undulatus (Sc un)" to me, usually they occur when weak updraft spreads horizontally and creates a thin layer(s) of puffy clouds which are then blown by strong winds into wave-like formations. It happens often here, if that is the same thing, it seems similar though.
They look like some form of orographic cloud...with an undoubted wave formation.

Some call them "mountain wave clouds".
Here we go again...

I've seen clouds exactly like this under an overcast deck.

To get us back on the right track though. My argument would be against Kelvin-Helmholzt waves, mainly because they look nothing like them.

I would also vote against mountain wave clouds. They are probably being influenced by the terrain, but they certainly aren't full blown lenticulars. It looks very city like in the photo.

Maybe you could tell us where this photo was taken and what time of year. What direction were you looking?
The clouds look wave oriented, that they do, and around eastern Tennessee mountain wave clouds, tend to move off off the root that is holding them together (the topography) and as the do, of course lose there structure and die. I did not pay attention to the foreground, I am mereley basing my judgements off of the clouds.
I agree with wave clouds. They are formed by wind interaction with terrain, similar to the interaction that produces lenticular clouds, just not as strong. I frequently saw them in east TN, and I've seen them a few times out here in OK. An interesting thing I've noted, particularly in TN...you can occassionaly get a rather sweet mammatus display in association with them.
I have seen clouds like these along and north of warmfronts a few times.


These images were shot on the morning of September 14, 2005 in the Flint Hills of SE KS.
Go here to find my chase report for that day.

Scott Currens
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Good day,

Those clouds are most likely oriented with some sort of turbulence caused by a lee wave (if a mountain is nearby) or even a surface boundary (front or outflow) in the vacinity. Quite interesting.

A true mountain wave cloud (taken from an aircraft) appears below...

Looks like a wave cloud to me. It would be interesting to know whether the trajectory of the 850 mb and 700 mb flow originated from any hilly areas or frontal zones. When I was in central Illinois, during southwest flow we sometimes saw nicely-formed wave clouds generated by the Ozarks a couple of hundred miles away... so it doesn't take much.
Hello gang!

I've seen this type of cloud formation several times around Montreal. The thing is I'm really not sure if it's caused by surface features, because around here there's no really big mountain, nothing higher than 800 meters in altitude for a couple of hundreds of kilometers from here.

I took this image of a similar pattern to Éric's pic:


I was told by our severe weather meteorologist that this type of feature is probably caused by some sort of wind sheer... honestly I don't know...

By the way, cool images Éric!
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I agree with Angie, Chris and TimV. Why? The cloud pattern suggests a wave cloud. Could be some other thing the atmosphere decided to create, but that's how it looks to me.

There were pics of some formations very similar to Gaetan's, submitted to the forum a couple of years ago, over SE Kansas. As I recall, a local TV met in Pittsburg use the term "lenticular mammatus." There was some speculation as to whether proximate gravity waves had anything to do with the formations, and there ensued some debate on the board as to whether "lenticular mammatus" was even a valid term. Whatever the proper term, seems pretty clear that some rare combination of processes not associated with topographical influence can produce such effects.
"lenticular mammatus"

Cool term! I don't really see anything wrong with calling them this. They do look like lenticulars and they have protuberances on the underside - not quite like an udder but probably close enough :)