In this case, a thin layer of it at about 30,000′, called cirrostratus nebulosus clouds.
Quite the pleasant surprise when you’re just going out to stretch your legs!
Other critters besides me were impressed. There was a pack of coyotes, sounded like a half dozen or more, howling away and carrying on something fierce. It sounded like they were down on the next street downhill from us to the west.