Allied bombing raids didn’t just devastate the cities of Germany and Nazi-occupied Europe. They damaged the heavens, too, new research shows.
Shock waves from the war’s big bombs reached 150 miles above the Earth’s surface, causing temporary damage to the ionosphere, the upper atmosphere.
The findings appeared September in Annales Geophysicae, the journal of the European Geosciences Union. Study coauthor Chris Scott of Britain’s University of Reading said he was “absolutely astonished” at the far-reaching impact of the Allied bombing campaigns. “Each raid released the energy of at least 300 lightning strikes.”
The researchers studied contemporaneous daily measurements of the ionosphere taken at the Radio Research Station near Slough, England. They decided to focus on the effects to the upper atmosphere during 152 major Allied bombing raids from 1943 to 1945.
They did not analyze German raids on London from September 1940 to May 1941 because the Blitz was so continuous it is difficult to separate its effects from seasonal factors. And German bombs typically were less powerful. While four-engine Allied bombers carried massive bombs such as the 12,000-pound “Tall Boy” and the 22,000-pound “Grand Slam,” the two-engine Luftwaffe bombers typically carried just 4,400 pounds of bombs.
The bomb blasts heated the upper atmosphere, weakening it by reducing the number of electrons. The damage from each raid typically lasted about 24 hours; the impact of the diminished ionosphere at the time isn’t clear, but the research helps explain why Allied airmen reported that their bombers were damaged by shock waves even when they flew above the recommended heights.
“What we get with these readings is a bit of detective work, which allows us a glimpse of not just what was happening on the ground but the effects of the bombing at the edge of space,” said Patrick Major, University of Reading historian and the study’s coauthor.
Researchers are keenly interested in the constantly changing ionosphere, which affects radio communications, radar, and GPS systems. The Annales Geophysicae study provides evidence of the ways that human activity can disturb the upper atmosphere.