| 2015-10-9 10:16:30 |
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Lightnings and Particle fluxes from the Thunderclouds Thunderstorms and Elementary Particle Acceleration
Yerevan, Armenia, 5-9 October 2015
The problem of how lightning is initiated inside thunderclouds
is probably one of the biggest mysteries in the atmospheric sciences. The
relationship between thundercloud electrification, lightning activity,
wide-band radio emission and particle fluxes has not been yet unambiguously
established. One of the most intriguing opportunities opened by the observation
of the high-energy processes in the atmosphere (so-called Thunderstorm ground
enhancements – TGEs) is their relation to lightning initiation. Lightnings and
TGEs are alternative mechanisms for discharging of the atmospheric “electric
engine” and synchronized observation of both phenomena helps to understand
better the both.
To discuss these high-energy phenomena, the conference on Thunderstorms and
Elementary Particle Acceleration was held at the Nor Amberd International
Conference Center of the Yerevan Physics Institute (YerPhI) in Armenia. The Cosmic
Ray Division of YerPhI and Skobeltsyn Institute of Nuclear Physics of Moscow
State University organized the workshop; YerPhI and the Armenian State
Committee of Science sponsored it. Thirty scientists and students from the
United States, Japan, France, Germany, Israel, Russia, and Armenia
attended.
Presentations focused on observations and models of the high-energy emissions
in thunderclouds; on termination of particle fluxes by lightnings; multivariate
observations of thunderstorm atmospheres from the earth’s surface and from the
space; radio emissions produced by atmospheric discharges and particle fluxes;
influence of the Extensive air showers (EASes) on lightning initiations and
others.
Discussions covered questions such as the following: Do particle fluxes
initiate lightnings? Do EASes helps to unleash -CG lightnings? Is TGE and TGF
currents competitive with lightning current? What is mechanism of particle flux
termination?
The workshop participants agreed that it would be useful to
compare vast amount of experimental data on TGE observed by Armenia, Japanese,
Slovakian and USA in various conditions by different particle detectors to
check the models of particle origin in thunderclouds. Armenia physicists
suggest to locate sensors developed by other groups at Aragats where large TGEs
are very often in Spring and Autumn.
With installing of new fast electronics at Aragats it became possible to relate
lightning initiation, fast and slow changes of the electric field and particle
fluxes on the millisecond scale. Various particle detectors and field meters
now are synchronized by GPS receivers providing time stamp with accuracy not
worse than few tens of nanosecond. The first large TGE was observed with
renewed ASEC facilities at 7 October 2015 during the workshop. The natural
“electron accelerator” on Aragats provides several interesting events, which
was intensively discussed by participants. During the most interesting 7
October TGE for the first time particle fluxes and lightning were detected on
millisecond time scale. On the one-second time scale the termination looks like
immediate decline due to deposition of large negative charge into the cloud by
the return stroke of lightning. However, on the millisecond time scale it was
evident that particle flux was declining successively along with distribution
of the deposited charge in the cloud.
The presentation slides and discussion videos are available on the conference website, http://crd.yerphi.am/Conferences/tepa2015/home. More details can be found in the supplemental information in the online version of this meeting report.
