In the TV show, early in the first season I assume that it is Damon controlling the fog and the crow? Is this stated in an episode somewhere?
It's pretty much said straight out in the pilot:
[Stefan enters his bedroom. A crow appears.]
[A man is standing on the balcony.]
Damon: Hello, brother.
STEFAN: Crow's a bit much, don't you think?
DAMON: Wait till you see what I can do with the fog.
In the series pilot (first episode), when Damon and Stefan meet for the first time after a 15-year break, Damon says as much.
I do not have the series on DVD, so cannot cite the exact dialogue. But he admits to the fog and the crow, while Stefan sort of ridicules over the theatrical means his brother employs.