I don't know all of the mechanics behind an inversion, but the end result is that the cold air is down while the warm air is up, and there's usually an odd cloud formation involved (see the layer of cloud sitting on the lake in the image below). In this case the cloud seemed to have trapped the frigid air right down on the lake, making it bitterly biting and difficult to go too far, especially for our two small dogs.
Shooting for Success: Mooses
1. Don't face directly at your prey, avoiding obvious eye contact. 2. Don't walk directly at your target, moving in at a variety of angles, so as to look casual and unconcerned.