As a student pilot studying for my meteorology exam, and with very little confidence in my cloud naming ability...I think they are stratus or altostratus (or a combination of both) and they imply stable weather.
I see stratus in them, but the regularity of the shapes make me wonder what is happening there, maybe there is a good amount of mixing going on which might make for turbulence below them. The wave aspect is interesting though. I'm wondering about the land under, if there are field-forest-field-forest.
In other words, I don't know and don't listen to me.
Meteorology is like opening up a whole can of worms. I've always felt like I wanted to learn about it, and now have to in order to pass my exam, and I find I like it a lot. I always wanted to "know" about weather, but intuitively knew it would be a nasty, unpredictable endeavor. Still, I try. The more I "learn" the more uncertain I become.
I knew more about weather before I started. Now I know less, but can go on about it much more.
Right now I'm arrogant enough to think I have an inkling about the Corialis effect, yet all information I find only ever talks about a high in the lower latitude forcing a wind towards the north, being affected. I can't figure out what happens when the high is more north than the southern low pressure area.
So, sorry, I really don't know.