AIR MAIL
Where today’s air came from
The air arriving over Dairyland about 5,000 feet above the ground was over the southern Plains three days ago, about 1,070 miles back along its path. Most of the nine paths traced from around the city agree. It came down from about 10,400 feet up, warming and drying as it sank. Near the ground the air came from a point about 460 miles to the south; at 10,000 feet, from the northern Rockies. Traced back 72 hours through NOAA’s hourly RAP analyses, nine paths at each of three heights.