News

Auroral crackling sounds are related to the electromagnetic resonances of the Earth

A new study shows that the sounds generated at an altitude of 70 to 80 metres are the result of the activation of Schumann resonances.
A graphic depicting the physics of auroral sounds

The study is a continuation of a hypothesis that Unto K. Laine, Professor Emeritus, published three years ago on the origin of the sounds heard during the displays of the Northern Lights. His theory postulated that the sounds are generated when a magnetic storm causes charges in the temperature inversion layer of the lower atmosphere, to be discharged at an altitude of 70 to 80 metres.

A recent research paper presented by Laine at the ICSV26 congress in Montreal provides a more detailed account of the sound generation. According to this study, when the Northern Lights occur, the spectrum of the temporal envelope of the crackling noise (or in other words, the rapid changes in the sound amplitude) contain frequencies of the Schumann resonances.

The Schumann resonances refer to the low-frequency electromagnetic resonances occurring around the Earth, the strongest of them being below 50 Hz. Laine has now observed that these resonances generated similar rhythmic structures in all the measured crackling sounds.

’Previous international research has shown that a geomagnetic storm occurring during the Northern Lights reinforces the Schumann resonances. For the first time, such resonances have been found to activate the sound generation mechanism in the temperature inversion layer at altitudes of between 70 to 80 metres where the accumulated electric charges give rise to corona discharges and crackling sounds. In addition to the nine lowest Schumann resonances, the spectra also include their difference and sum frequencies or in other words, distortion components. This non-linearity also lends support to the hypothesis of auroral sounds generation,’ Laine says.

The research material consisted of 25 sound events measured on the ground in September 2001 and in March 2012 in Southern Finland, during the display of active Northern Lights. Although the measurements were conducted at different locations using various equipment, the results nevertheless point to the same direction.

The results will be published today (10 July) at the ICSV26 congress in Montreal, which brings together more than 2,000 researchers in acoustics from around the globe.

 

Further information:

Unto K. Laine, Professor Emeritus

[email protected]

 

  • Published:
  • Updated:
Share
URL copied!

Related news

two men shaking hands
Honoured, Research & Art Published:

Metex Prize to Ville Piippo

The thesis, in the field of design, focuses on driving ergonomics and sustainable design of an electric motorbike.
Janne Lindqvist seisoo mustassa puvussa taustallaan Aallon A-kirjainvalotaulu ja valotaideteos seinällä
Research & Art Published:

Janne Lindqvist is the first person in Finland to receive a Mozilla Research Grant – supports making the internet a better place

The Mozilla Foundation awards researchers with unrestricted gifts, which makes them highly competitive
Janne Lindqvist
Research & Art Published:

Janne Lindqvist: You can’t help if you stay in the ivory tower

This sociable professor of computer science knows how to forge his own path and trusts his instinctive curiosity towards different research topics.
maankäyttö
Press releases, Research & Art Published:

Feeding the world without wrecking the planet is possible

Almost half of current food production is harmful to our planet – causing biodiversity loss, ecosystem degradation and water stress. But as world population continues to grow, can that last?