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Dejan Vinković

Science and Society Synergy Institute
Bana Jospia Jelacica 22B
40000 Cakovec, Croatia
e-mail: dejan_at_iszd.hr
Electrophonic Sounds and ELF/VLF Radio Emission from Meteors
Active Project
Latest update: July 20, 2006
SEE ALSO: Research Expedition to Mongolia 1998

SEE ALSO: Global Electrophonic Fireball Survey

Video images of a meteor that produced an electrophonic sound. You can download the movie here (the moment of electrophonic sound is marked with "E").
Meteors produce two types of sound---normal and anomalous (electrophonic). The latter lack a time delay between the visual appearance of the meteor and audible detection on the ground, an apparent contradiction recognized more than 300 years ago. These sounds most probably result from corona discharge and vibration of objects due to a local quasi-electrostatic (ELF/VLF frequency range) enhancement of the electric field (Vinkovic et al. 2002, WGN-JIMO, 30, 244). However, the physical mechanism of electric field amplification by a meteor is still a complete mystery. In 1998 I helped organize the Croatian Physical Society expedition to Mongolia to detect the ELF/VLF radio emission and electrophonic sounds from the Leonid meteor shower. We succeeded in obtaining the first ever instrumental recording of meteor electrophonic sounds (Zgrablic et al, JGR 2002, 107(A7); see also fizika.org/ilwcro/results). Post-analysis shows that all the existing theories fail to explain the observations. The results represent a milestone in this field of study. I am currently coordinating the Global Electrophonic Fireball Survey (www.gefsproject.org), a project that studies the phenomenon and collects witness reports.

Zgrablic, G., Vinkovic, D., Gradecak, S., Kovacic, D., Biliskov, N., Grbac, N., Andreic, Z, & Garaj, S. 2002, Journal of Geophysical Research (Space Physics), 107, 11 (ADS, PDF)

Garaj, S., Vinkovic, D., Zgrablic, G., Kovacic, D., Gradecak, S., Biliskov, N., Grbac, N., & Andreic, Z. 1999, Fizika A, 8, 91 (ADS, PDF)

Vinkovic, D., Garaj, S., Lim, P.L., Kovacic, D., Zgrablic, G., & Andreic, Z., 2002, WGN, Journal of the International Meteor Organization, 30, 244 (ADS, PDF)

Vinkovic, D., Andreic, Z., Garaj, S., Kovacic, D., Mladinov, M., & Zgrablic, G. 2000, WGN, Journal of the International Meteor Organization, 28, 48 (ADS, PDF)

Spectral distribution (sound amplitude .vs. sound frequency .vs. time) of two electrophonic sounds detected during the expedition to Mongolia in 1998. Each electrophonic sound was detected on two separate microphones. Left column: the sound from the -6.5m fireball; Right column: the sound from the -12m fireball; Color: relative sound amplitude in dB.
See Zgrablic et al. 2002, JGR (Space Physics), 107, 11 (PDF) for more information.