AIR MAIL
Where today’s air came from
The air arriving over Hartsville about 5,000 feet above the ground was over the western Atlantic three days ago, and over the Great Lakes a day ago, about 1,250 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 the Atlantic off the Carolinas. Traced back 72 hours through NOAA’s hourly RAP analyses and the GFS beyond them, nine paths at each of three heights.