A solar-powered balloon launched into Earth’s stratosphere has recorded a series of mysterious rumbling sounds that scientists have been unable to pinpoint their origins.
This noise is known as infrasound because it is detected by special equipment 70,000 feet above the earth’s surface and is too low to be heard by the human ear. Selected among the hidden infrasounds of thunder, sea waves, rocket launches, cities, wind turbines, and even planes, trains, and cars, this strange infrasound has so far left no explanation. there was no
”[In the stratosphere,] Some flights are emitting mysterious infrasound signals several times an hour, the source of which is completely unknown,” said Daniel Bowman, principal investigator at Sandia National Laboratories in New Mexico, in a statement. said in
The stratosphere begins about 9 miles (14.5 km) above the Earth’s surface and extends upward to a height of about 31 miles (50 km). The stratosphere is the layer of the atmosphere above our planet. The stratosphere is filled with ozone that blocks ultraviolet rays and is a calm place with little turbulence. Most of the sound at this altitude comes from infrasound reflections from the earth’s surface.
Scientists and amateur investigators have been flying balloons into the stratosphere since the 1890s. His one of the first microphonic balloon experiments, a top secret military experiment project Moguls, designed to detect the sounds of Soviet atomic bomb tests in the late 1940s, crash-landed in Roswell, New Mexico in 1947, It led to the cover-up that sparked the UFO conspiracy. theory to date.
To sample the stratospheric soundscape, Bowman and colleagues built a series of 7-meter (23-foot) wide plastic balloons, anchored them with infrasound sensors called microbarometers, and added charcoal powder. . Due to the darkening properties of charcoal, sunlight heats the air inside the balloon, causing it to float.
“Our balloons are basically giant plastic bags that are blackened with charcoal dust on the inside. It’s made with corn flour,” Bowman said. “When the sun hits a black balloon, it heats the air inside, increasing its buoyancy. is.”
Starting with the first balloon launch in 2016, researchers sent 50 balloons into the sky to sample the low booms and roars of the stratosphere. The researchers initially set out to record the sounds of volcanic eruptions, but then used GPS to track the balloons over hundreds of miles of flight paths and study other sounds they picked up.
It was during these flights that the researchers picked up the sounds. The signal was a low, repetitive rumbling that could not be traced. Scientists have some idea of what these mysterious noises might be, and their range ranges from previously undetected forms of atmospheric turbulence to imperceptibly garbled sounds from below. It ranges from the echo of .
The researchers said they will continue to explore sounds in the stratosphere, tracking more sounds to their point of origin, and studying their variation across seasons and different regions of the world.
The researchers presented their findings at the Acoustical Society of America’s 184th meeting in Chicago on May 11.
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