Neil Robbescheuten, 62, wasice fishingona Canadian lake when a zero-visibility fog snuck in and knocked his bearings for a loop. He was in a proverbial fog and clueless as to his own – or anyone else’s – whereabouts.

Hey, I’ve been ensnared in just such a sky trap, down on little Collins Cove, Mullica River. The fog was on me in a muffled flash. Things went from eagle-watchingly clear skies to sights out within a few minutes. I can assure that an instantaneous fog atop ice is surreal.