Image of the Earth taken from a hot air balloon – Photo: YAHOO NEWS
These noises are detected by specialized instruments on a hot air balloon in the stratosphere. They are called infrasound because they are so low pitched that the human ear cannot hear them.
The stratosphere is located just above the Earth’s atmosphere, starting at a distance of 14.5 km above the Earth’s surface and extending to an altitude of about 50 km. They are filled with ozone blocking ultraviolet rays, are a quiet place with less disturbance.
“In the stratosphere, mysterious acoustic signals appear several times an hour, but the source of these signals is completely unknown,” said principal investigator Daniel Bowman, senior scientist at the Department of Science and Technology. Mexico (USA) said.
A variety of sounds – including thunder, ocean waves, rocket launches, cities, wind turbines and even planes, trains and cars – when infrasonic still cannot explain the strange sounds.
To experience the sound from the stratosphere, Bowman and his colleagues built a series of 7-meter-wide plastic balloons. The team trapped them with ultrasonic sensors called microbarometers and added charcoal dust.
The blackening properties of charcoal allow sunlight to heat the air inside the balloon, causing it to rise. This passive solar energy is enough to lift a hot air balloon from the Earth’s surface to more than 20 km high.
The researchers sent 50 balloons into the sky to test the rumbles and rumbles from the stratosphere.
It was during these flights that the researchers picked up the sounds — the deep, periodic rumbles that the signal couldn’t track.
Scientists are suspecting that these mysterious noises could be a form of atmospheric disturbance that hasn’t been detected before.
The team’s investigation into stratospheric sounds will continue. They traced more types of sounds back to their source. Also study the change of sound through the seasons and different regions of the world.
The team’s findings were presented at the 184th May 11 meeting of the American Acoustical Society in Chicago.
