My wife and daughter captured some pictures of these contrails near Stonehaven in Aberdeenshire yesterday, August 26th. We have pored over the picture at work (it's a professional meteorological office with some very experienced forecasters) and so far none of us can come up with a convincing explanation.

Anyone out there have any theory about what we are seeing?

Could be military activity - as in formation flying.  Get lots of that over Anglesey etc.  The curves are just the different speeds of the air thats its in - moving .

It's hard to say but it looks like the trails are from aircraft climbing steeply?
So they could well be going through layers moving at different speeds.

There are a lot of events on almost daily just now so an increased likelihood of spotting some display team practicing or on the way to something.

Thanks for the suggestions.

I agree it's hard to work out what the vertical extent is - we were thinking the trails were more on a horizontal plane

Military formation flying is one of the few things that makes sense, although I've never seen trails like that before up here. Usually the formation flying is done much lower down, and these appear to be contrails so must be getting up towards normal civilian flight cruising levels.