The white stuff on the trees is litterally frozen fog, not snow.
It freezes in the direction the fog is rolling.
When the fog lifts, this will completely melt in 10 minutes.
So, you sit in a parking lot and wait for the fog to lift, then shoot like crazy!
You'll notice I get "full tree" shots in the sun...
Then, I have to move to the shadows to get macros, because it melts too quickly.
(click next to see a macro of the shape this fog creates)


More winter scenes can be found here: