It's that time of the year that the water temperatures of the lakes and rivers in Middle Tennessee are still warm.
So when the air temperature gets chilly, steam fog forms.
Notice that in the first picture from the News 2 City Cam, you can't see the river, or the stadium and East Nashville.
The Cumberland River is running 67°, while the air above it this morning dropped to 37°-39°. That 30 degree difference created the fog.
Although the water is not boiling, it is called "steam fog" because the water vapor molecules rise from the warmer water into the cold air and condense into fog.
The picture looking towards downtown from the Adventure Science Center even looks like steam!
The last picture is from Cedar Hill Resort at Dale Hollow Lake.