I was at a weather conference last fall for both pilots and meteorologists, and in one of the presentations, the pilot-presenter had a slide filled with clouds like you show. She flies out of an airport north of Taos, and her presentation was all about the 'signposts in the sky.'
One of the audience members asked her what those clouds told her, and she answered that there was, temporarily at least, a stable layer capping off the vertical development. In the case of her particular flight, she used this info to determine that she could proceed the 30-45 minutes she needed to before convection took over and led to more development.
We call them jellyfish clouds here, too.