AIR MAIL
Where today’s air came from
The air arriving over New Bremen about 5,000 feet above the ground was over the western Atlantic three days ago, and over New England a day ago, about 860 miles back along its path. It came down from about 12,600 feet up, warming and drying as it sank. Near the ground the air came from the western Atlantic; at 10,000 feet, from Quebec. It feels dry all the same. Traced back 72 hours through NOAA’s hourly RAP analyses and the GFS beyond them, nine paths at each of three heights.