AIR MAIL
Where today’s air came from
The air arriving over Clyde about 5,000 feet above the ground was over the Pacific Northwest three days ago, and over the Great Lakes a day ago, about 1,890 miles back along its path. Most of the nine paths traced from around the city agree. It came down from about 9,500 feet up, warming and drying as it sank. Near the ground the air came from Quebec; at 10,000 feet, from the California coast. Traced back 72 hours through NOAA’s hourly RAP analyses, nine paths at each of three heights.