The aeronomical pilgrim's progress

Herein are recounted one aeronomer's recollections of how some advances in our understanding of how the Earth's upper atmosphere works were made during the quarter century beginning in 1950. That period was selected because it spans about half of his aeronomical career and ends at a time when there was a discontinuity in that career. During that time, aeronomers achieved a first‐order understanding of Earth's thermosphere and exosphere. Afterward many of them, including the author, became preoccupied with other problems.