In reply to CantClimbTom:
Thanks for the link. I’m stuck in my home office this afternoon for some calls, watching them come and go in the distance. They’re not as distinct as on Sunday but are still captivating.
After reading your link I now see each one as a projection of a distinct fell on to the sky; I’m imagining an AR app that triangulates them for distance using a pair of phones, and that using wind speed data and a terrain map to find their sources, overlaying each cloud the name of the fell making it.