AIR MAIL
Where today’s air came from
The air arriving over White about 5,000 feet above the ground was over the central Plains three days ago, and over the southern Plains a day ago, about 1,130 miles back along its path. It came down from about 11,600 feet up, warming and drying as it sank. Near the ground the air came from a point about 540 miles to the south; at 10,000 feet, from the Great Basin. Traced back 72 hours through NOAA’s hourly RAP analyses, nine paths at each of three heights.