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!

Read more news

A green laser light shining on a sample stage between two magnets
Press releases, Research & Art Published:

New nanoscale device for spin technology

Spin waves could unlock the next generation of computer technology, a new component allows physicists to control them
Apulaisprof. Emma-Riikka Myllymäki
Research & Art Published:

Emma-Riikka Myllymäki: Why company reporting needs to be excellent

By producing high-quality reports on both their business and sustainability impacts, companies build trust and aid stakeholder decision-making.
SSD21 banner
Research & Art Published:

Our un­will­ing­ness to sac­ri­fice com­fort: 3 ta­boos pre­vent­ing sustainable trans­form­a­tion

Why is it so difficult for us to change our current practices for more sustainable ones? Are there any explicit taboos that hinder decision-making? Sustainability Science Days, Finland’s largest event in sustainability science, addresses sustainability challenges, including both taboos and innovative ways of promoting sustainability.
Kerrostalo ja kallioita
Cooperation, Press releases, Research & Art Published:

The SUBURBAN PRIDE project examines the relationship between mental images of suburbs and the built environment

The multidisciplinary project combines history of architecture, sociology, and research in critical cultural heritage and landscape architecture. The purpose of the project, based on research and workshops, is to build a sustainable future for suburbs.