String cloud in Hartlepool

If you enlarge the photo, just up and right of the top of the nearest street light there is some faint wispy cloud. The picture hasn't quite conveyed what I saw but there seemed to be thin delicate lines of cloud like strings. This is a minimal form of the mackerel sky I've posted about before. It isn't lenticular cloud but I know that lenticular cloud is caused by stationary wave patterns where vapour condenses into the antinodes. This is such a regular periodic pattern with condensed vapour  between clear gaps that I'm wondering if it might be some kind of stationary wave.