I always laugh when I hear NBC 'Today Show' meteorologist, Al Roker say: " Cold air coming down from Canada...."
Truth is, this cold northern air originates at the North Pole, comes through the Arctic region, then through Canada and on into the United States.
That's what happens.
This cold air doesn't originate in Canada but transits through Canada before reaching the United States.
And no wall could restrict this cold air flow.
Canadians suffer through these cold, dark winter months just the same as a good deal of the U.S. population.
All that aside, that's a nice shot you took with your P3 4K.