AIR MAIL
Where today’s air came from
The air arriving over Hancock about 5,000 feet above the ground was over the western Atlantic three days ago, about 1,770 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 Canada; at 10,000 feet, from a point about 460 miles to the south. Traced back 72 hours through NOAA’s hourly RAP analyses and the GFS beyond them, nine paths at each of three heights.