AIR MAIL
Where today’s air came from
The air arriving over Moravia about 5,000 feet above the ground was over the western Atlantic three days ago, and over Quebec a day ago, about 1,040 miles back along its path. It came down from about 9,000 feet up, warming and drying as it sank. Near the ground the air came from a point about 770 miles to the northeast; at 10,000 feet, from the western Atlantic. Traced back 72 hours through NOAA’s hourly RAP analyses and the GFS beyond them, nine paths at each of three heights.