Not including the first dragon that you slay in Skyrim as part of the main quest, what was the first 'dynamic' dragon encounter you had?

For me, it was heading up to High Hrothgar.

I got past the third emblem and the shadow of a dragon swooped over head and spiralled away over the mountains. I readied, tensed... but he didn't come back.

And then I headed up the path and was torn apart by a frost troll. Really hating trolls at the moment.

I reloaded and this time the dragon attacked, ice flavour. There was lots of flying around and screaming and wailing and it landed up the path momentarily.

Anyway, after slaying the beast I found the troll was nowhere to be seen.

Was this scripted? The troll a barrier to my progression until I had another soul? Or a dynamic event?

Im guessing the troll is scripted because Ive come accross him aswell. My first dynamic dragon was when i was wandering to Falkrieth, landed right infront of me without any sound and I pooped my pants.