26/09/2018 11:11 BST | Updated 26/09/2018 15:20 BST

Shockwaves From Second World War Bombing Raids Reached The Edge Of Space

Bombs dropped by Allied planes were big enough to weaken the electrified upper atmosphere, experts say.

Shockwaves from bombing raids by Allied forces during the Second World War reached the edge of space, scientists have discovered. 

The findings could help reveal how natural disasters such as earthquakes, volcanoes and even thunderstorms affect the Earth’s atmosphere, according to new research.

Examining data gathered by British wartime scientists, researchers from the University of Reading found the shockwaves produced by huge bombs dropped by Allied planes on European cities were big enough to weaken the electrified upper atmosphere – the ionosphere – above the UK, 1,000km away.

National Archives and Records Administration
A raid by the 8th Air Force on the Focke Wulf factory at Marienburg, Germany (1943)

Researchers looked at daily records collected between 1943-45 at the Radio research Centre in Ditton Park in Slough for the study.

Sequences of radio pulses over a range of shortwave frequencies were sent 100-300km above the Earth’s surface to reveal the height and electron concentration of ionisation within the upper atmosphere.

When studying the ionosphere response records around the time of 152 large Allied air raids in Europe, researchers found the electron concentration significantly decreased due to the shockwaves caused by the bombs detonating near the Earth’s surface.

This is thought to have heated the upper atmosphere, which enhanced the loss of ionisation.

Chris Scott, professor of space and atmospheric physics at Reading, said: “The work at Slough was routinely analysing the height and intensity of these layers to understand how they vary, but what they didn’t realise at the time was that they actually contained the signatures of the war itself.”

University of Reading
Damage from bombing during WWII around Frankfurt Cathedral.

Detailed records of the Allied raids reveal their four-engine planes routinely carried much larger bombs than the German Luftwaffe’s two-engine planes could. These included the ‘Grand Slam’, which weighed up to 10 tonnes.

Prof Scott added: “The images of neighbourhoods across Europe reduced to rubble due to wartime air raids are a lasting reminder of the destruction that can be caused by man-made explosions. But the impact of these bombs way up in the Earth’s atmosphere has never been realised until now.

“It is astonishing to see how the ripples caused by man-made explosions can affect the edge of space. Each raid released the energy of at least 300 lightning strikes. The sheer power involved has allowed us to quantify how events on the Earth’s surface can also affect the ionosphere.”

Professor Patrick Major, University of Reading historian and a co-author of the study, said: “Aircrew involved in the raids reported having their aircraft damaged by the bomb shockwaves, despite being above the recommended height.

“Residents under the bombs would routinely recall being thrown through the air by the pressure waves of air mines exploding, and window casements and doors would be blown off their hinges.

“There were even rumours that wrapping wet towels around the face might save those in shelters from having their lungs collapsed by blast waves, which would leave victims otherwise externally untouched.”

Prof Major added that the “unprecedented power” of such attacks has proved useful for scientists to gauge the impact such events can have hundreds of kilometres above the Earth, “in addition to the devastation they caused on the ground”.

The researchers are planning to digitise more early atmospheric data so they can understand the impact of the many hundreds of smaller bombing raids during the war, and help determine the minimum explosive energy required to trigger a detectable response in the ionosphere.