Scientists discover perplexing low-frequency noises in the Earth's atmosphere

Scientists have discovered mysterious sounds in the Earth’s stratosphere, the origins of which are unknown to the researchers.

Unexplainable, low-frequency sounds in the Earth's atmosphere are leaving scientists scratching their heads.

A group of scientists from Sandia National Laboratories have detected mysterious recurring sounds in the Earth’s stratosphere, the origins of which are unknown to experts.

“[In the stratosphere,] there are mysterious infrasound signals that occur a few times per hour on some flights, but the source of these is completely unknown,” said Daniel Bowman, senior scientist at Sandia National Laboratories in New Mexico, in a press release.

The stratosphere is a layer of the Earth’s atmosphere, and is known to be a relatively calm environment where sounds can be heard that may not be picked up elsewhere, as it is filled with ultraviolet-blocking ozone.

At a height of 21,336 metres, the low-frequency noises were detected by solar-powered balloons sent out to pick up on different sounds.

The balloons, which Bowman describes in a press release as looking like giant plastic bags, were about seven metres wide, and were fastened with infrasound sensors, called microbarometers.

To make the balloons float, they filled them with charcoal dust, making them dark enough to allow sunlight to heat up the air in the balloon.