I was out last night and came home around 11.30. The sitting room windows appeared to have a chalky film on them and when I have zoomed the photo closer there is a weird pattern visible. I have never seen this on my windows.
I've attached three pictures. Two with the weird substance in the them and one of it and one looking entirely normal this morning.
What on earth is it? If I hadn't taken photos I would have thought that I'd overdosed on Prosecco and been hallucinating!