Here's the deal:
I was on my second character, a Nord warrior. Before starting the main quest, I decided to do a little exploring first, so after hitting up Riverwood I went directly west and kept travelling across the plains, leveling up and killing stuff as I went along. I finally came upon the Reach, and was a few minutes into the land, when I experienced the all-too-familiar screen shake and rumbling-esque noise of a dragon flying overhead. The problem? I hadn't started the main quest, and there was no dragon to speak of. I was just walking along the main road heading towards a bridge, and the screen shook and there was a rumbling noise, and then nothing. Nothing happened, other than that.
Skip ahead to my third character, an Altmer mage. Again, putting off the main quest to go along and do my own thing for a while. Heading west along the northern areas of Skyrim, going from Winterhold to Dawnstar, then ultimately going from Solitude to Markarth. Upon entering the Reach and heading down a hill, I encountered the same exact screen tremor and rumble noise. And again, I was met with absolutely nothing in sight to have possibly caused it. No dragon. No troll. No giant. Nothing. It was just my character surrounded by a thin layer of fog.
I went on to create a handful of more characters and play hundreds of more hours. This event only happened once per character, and it only happened when I *walked* into the Reach, never when I took the carriage to Markarth. I *never* experienced it if I wasn't directly walking into the Reach. And it's only happened in the Reach...different areas of the Reach, but absolutely only the Reach, and it was foggy each time.
I don't know if the fog is important or not. Does Alduin fly around and make appearance before the main quest is started? I guess it could be him, but I've never seen him anywhere before I actually started the main quest.
So yeah, if anyone could shed some light on this, I'd be appreciative, as I'm apparently not the only person to experience this (brief discussion about it on another thread) and we're all equally clueless.
