AIR MAIL
Where today’s air came from
The air arriving over Weymouth about 5,000 feet above the ground was over the Atlantic off the Carolinas three days ago, and over the Great Lakes a day ago, about 1,610 miles back along its path. Most of the nine paths traced from around the city agree. Near the ground the air came from the western Atlantic; at 10,000 feet, from New England. Traced back 72 hours through NOAA’s hourly RAP analyses and the GFS beyond them, nine paths at each of three heights.