AIR MAIL
Where today’s air came from
The air arriving over Yarmouth about 5,000 feet above the ground was over the Mid-Atlantic three days ago, and over New England a day ago, about 1,000 miles back along its path. The nine paths traced from around the city fan out, so treat that as a best guess. It rose from near the ground on the way. Near the ground the air came from the North Atlantic; at 10,000 feet, from a point about 190 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.