The shock waves caused by the bombs of the Second World War were at the edge of the space

Nearly 80 years later, the violent bombings of the Second World War still have repercussions all over the world. Christopher Scott would know – two of his aunts were killed at the age of 9 and 11 at the London Blitz, the eight-month attack on Nazi Germany against the British.

These air raids have not only affected generations of families. Scott, a physicist of space and atmosphere at the University of Reading in the UK, recently discovered that bombs were also felt at the edge of space.

By combining archival data, Scott discovered that shockwaves from bombs briefly weakened the ionosphere, the outermost layer of the Earth's atmosphere. [10 of the Most Powerful Explosions Ever]

From lightning to bombs

Between 50 and 375 miles (80 and 600 kilometers) above ground level, the ionosphere is where auroras are created and where astronauts live aboard the International Space Station. The gas atoms in this layer of the atmosphere are excited by solar radiation, forming electrically charged ions. The density and altitude of electrons, negatively charged particles, in the ionosphere can fluctuate. [Infographic: Earth’s Atmosphere Top to Bottom]

"The ionosphere is much more variable than can explain solar activity," said Scott Live Science.

Scott's previous research had shown that lightning could improve the ionosphere. He wanted to know if this was due to the explosive energy of the lightning or its electrical charge. He therefore searched for well-documented field explosions and compared historical data with archived data from the Slough Radio Research Center, where scientists had measured ionospheric density using radio pulses sent over a short-wave frequency range. .

Scott said he initially intended to look into the effects of the London Blitz, but little information was provided on the timing and ammunition used for these raids. As an alternative, Scott's colleague, Patrick Major, a historian at the University of Reading, provided a database on the Berlin bombing between 1943 and 1944 and directed Scott to other datasets on Allied Air Raids. in Europe.

Shockwaves

Each raid released at least 300 lightning strikes, Scott said, and historical stories on the ground attest to the sheer power of bombs like the 22,000 pounds. (10,000 kilograms) British "Grand Slam."

"People living under the bombs would regularly remember being thrown into the air by the pressure waves of the exploding air mines, and the windows and doors would have been torn off their hinges," Major said in a statement.

When researchers looked at ionospheric response recordings at the time of 152 major Allied air strikes in Europe, they found that the concentration of electrons decreased significantly due to shock waves from bombs. The results were published today (25 September) in the journal Annales Geophysicae.

"I've seen an effect in the United States on the ionospheric archives of the bombing over 1,000 km [620 miles] away, "said Scott. "I was surprised by that."

Ingo Mueller-Wodarg, a global scientist from Imperial College London who did not participate in the study, said the research was "a clear demonstration of the impact of the ionosphere on the soil, even if soil . "

The effects of shockwaves would be temporary, Scott said, for less than a day. "The ionosphere is largely controlled by solar radiation," he told Live Science. "The bombing is a small impact by comparison."

Scott added that the weakening of the ionosphere may have affected the efficiency of short wave radio communication, which depends on the ionosphere to reflect signals over long distances.

More modern technologies, such as GPS, are affected by ionospheric disturbances. Another study released earlier this year showed that the massive shock wave caused by the launch of a SpaceX Falcon 9 rocket in 2017 has created a temporary hole in the ionosphere, which may have disrupted navigation signals for an hour or two.

Next steps

Mueller-Wodarg noted that speculation has long focused on the impact of earthquakes on the ionosphere, with mixed results. "This study strongly supports the suggestion that events on the ground that generate all kinds of shock waves or strong impulses should be felt in the ionosphere," said Mueller-Wodargtold Live Science.

Scott said he also wanted to know if thunderstorms, volcanoes and earthquakes could be detected using similar methods.

It is also digitizing previous UK ionospheric data with the intention of putting this information online so that volunteers can help identify more effects on the ionosphere. This could help Scott understand why lightning has an impact on the ionosphere.

"The ionospheric layer we saw responding to the bombing was much higher than that used in the lightning study because it was the only one for which there is currently digital data," Scott said. "That's one of the reasons I want to digitize ionospheric data, so we can see if the bombardment improves the lightning-enhanced layer. Only then can we say for sure whether the effect of lightning is due to shock waves or electric current, or both.

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