Manifestation of thunderstorm processes in low-frequency radiation

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In this work we consider some features of characteristics of electromagnetic signals in the ELF range, ac-
companying thunderstorm VLF signals (atmospherics) and with which red transient luminous glows (sprites)
at the mesosphere and the lower ionosphere heights are associated. Signals were recorded at high latitudes in
very favorable conditions from the point of view of absence of any electric power and industrial radio noise.
The radiation is observed at the frequencies below 1 kHz usually in the form of two half-period fluctuations
(ELF impulses) and it follows with a delay relative to the corresponding atmospherics within the range of 0-7
ms. In the recorded signals on August 21-23, 2008 ELF fluctuations in most cases were observed 1 and 3 ms
later, and in 14 % of events delay was absent. Events of quasi-periodic ELF fluctuations with the period of
fluctuations of about 7 ms (frequency of 143 Hz), corresponding to the quasi-period of ELF impulses accompa-
nying atmospherics were detected. In each period of the wave form of fluctuations an additional smaller peak
may exist. Fluctuations in short (dt <100 ms) events actually perform atmospherics role, which are followed
by pulse of 2 half-cycles at lower frequency fluctuations (in comparison with 7 ms). Characteristics of long ELF
fluctuations indicate resonance character of the phenomenon and an opportunity of long "feed" the probable
resonator during thunderstorm activity.
The work is supported by Russian Foundation for Basic Research grants 08-02-00348-а, 09-05-98540-р_vostok_а
and Presidium RAS Programs №16, RNP 2.1.1/2555.