I believe it is called attic rain. Our home inspector brought it up when we bought our home a few years ago. He took me up and showed me where the condensation was building up, where it originated from, and what had to happen to seal it off. We had a list for the owners of things to fix and this was one of them.
I pulled up the old repair email and this was the scope of work:
It was all organized by our previous owner, looks like it was repaired by
Leading Edge Calgary