AIR MAIL
Where today’s air came from
The air arriving over Newburg about 5,000 feet above the ground was over a point about 310 miles to the south three days ago, and over the Mississippi Valley a day ago, about 640 miles back along its path. Most of the nine paths traced from around the city agree. It came down from about 9,000 feet up, warming and drying as it sank. Near the ground the air came from the Great Lakes; at 10,000 feet, from the southern Plains. Traced back 72 hours through NOAA’s hourly RAP analyses, nine paths at each of three heights.