AIR MAIL
Where today’s air came from
The air arriving over Oakwood about 5,000 feet above the ground was over a point about 290 miles to the south three days ago, about 670 miles back along its path. Most of the nine paths traced from around the city agree. It came down from about 8,900 feet up, warming and drying as it sank. Near the ground the air came from the Great Lakes; at 10,000 feet, from the central Plains. Traced back 72 hours through NOAA’s hourly RAP analyses, nine paths at each of three heights.