AIR MAIL
Where today’s air came from
The air arriving over Fort Fairfield about 5,000 feet above the ground was over the North Atlantic three days ago, and over the western Atlantic a day ago, about 1,170 miles back along its path. Most of the nine paths traced from around the city agree. It rose from near the ground on the way. Near the ground the air came from a point about 370 miles to the northeast; at 10,000 feet, from the Great Lakes. Traced back 72 hours through NOAA’s hourly RAP analyses and the GFS beyond them, nine paths at each of three heights.