28
high-altitude discharges from 3 to 16 events were recorded, and single events
occurred much less frequently than the series. Registration of flashes took place
in the ultraviolet (240–400 nm) and red-infrared (610–800 nm) ranges of the
night-time atmosphere emission spectrum [71].
A number of studies on modeling the electrical and
chemical processes during
fast discharge phenomena were carried out. Further development of the theory
of discharge phenomena in the stratosphere and mesosphere (elves and sprites),
which are initiated by tropospheric storm processes, was discussed in [72]. The
redistribution of charges in the atmosphere was investigated quantitatively at the
altitudes up to 150 km during the process of charging and discharging of a thun‑
dercloud. Long duration of high altitude discharges, which are developing in the
residual polarization field, was explained by taking into account small electrical
conductivity of the atmosphere.
The paper [73] was devoted to the study of the conditions for the initiation
of two types of high-altitude discharges, sprites and halo. A quasi-electrostatic
model was developed for generating the electric field in the middle atmosphere,
which takes into account peculiarities of the charge distribution and its dynamics
inside thundercloud, as well as the realistic atmospheric conductivity profile.
Non-linear effects associated with the heating of electrons in the electric field
were also considered. It was shown that the area where the electric field of the
lightning flash exceeds the breakdown field, is centered around an altitude of
about 75 km, which is consistent with the observations of sprites. It was found
that the dynamics of the current and charge of the lightning flash plays an essen‑
tial role in the initiation of high-altitude discharges in the atmosphere.
The influence of high-altitude discharges on the chemical composition of the
mesosphere was investigated in [74,75] on the basis of a numerical model; a
self-consistent plasma-chemical model was suggested for the diffusion region of
a sprite in the altitude range 60–90 km. Perturbations were analyzed of the con‑
centrations of ions, electrons and neutral components
due to a sprite discharge
and of the intensity of photon emission due to a sprite or a halo. Owing to the
rapid displacement of the electric field at the top of the diffusion region of a sprite
at the altitudes 78–81 km, the radiation at the discharge axis ceases earlier than
in the outer region, i. e., toroidal structure of the electric field and sprite radiation
is being formed. The electron density decreases during the development of a
sprite discharge at the altitudes 83–87 km, which is the result of the increasing
role of dissociative attachment to molecular oxygen, which significantly reduces
the conductivity at these altitudes.
A number of studies were dedicated to the problem
of initiation of lightning
discharges and the runaway breakdown. The possibility of a self-discharge in a
transverse field of a lightning leader in the regime of generating relativistic run‑
away electron avalanches was analyzed in [68]. A low threshold for feedback
E. A. Mareev, V. N. Stasenko, A. A. Bulatov, S. O. Dementyeva, A. A. Evtushenko, N. V. Ilin, ...
29
Atmospheric
Electricity
was obtained for a leader of cylindrical geometry. It was shown that the discharge
can be the source of the pulses of penetrating radiation observed to be correlated
with thunderstorm activity; the characteristics of these pulses were reproduced
in the model of a cylindrical leader.
The data obtained from the simultaneous recording
of signals emitted during
lightning discharges in the radio and gamma‑ray ranges during the in situ obser‑
vations in the Tien Shan were analyzed in [63, 76]. High correlation (0.9–0.95)
between gamma waves and radio waves was shown. Measurements confirmed
the theory of lightning initiation by relativistic runaway electron avalanches. It
was demonstrated that the energy spectrum of gamma radiation corresponds to
the characteristic spectrum of the runaway breakdown. In [76] detailed analysis
was performed of the dynamics of electric pulses during the development of a
lightning discharge, which indicated that the breakdown is determined by the
runaway electrons. High magnitude of current pulses was explained by multiple
micro-discharges on the hydrometeors, as a result of which, the vast region of
ionic conductivity is formed in the cloud. It was shown that the charge transfer
by ions plays a decisive part in the development of a lightning leader.
Conclusions
Over the last few years the studies of atmospheric electricity in Russian Fed‑
eration have been actively being developed. A variety of experimental and theo‑
retical studies of fair weather electricity, including the impact of atmospheric
ions and aerosols, were performed. Experimental and theoretical research regard‑
ing the global electric circuit was carried out with the help of models of climate
and chemistry. A numerical non-stationary three-dimensional model of a convec‑
tive cloud allowing for the electrification was constructed, and a model of the
cloud dynamics have been developed with a detailed description of microphys‑
ics. A number of experimental studies in the fields of lightning physics and light‑
ning protection were performed, including experiments employing unique labo‑
ratory equipment and field experiments at the All-Russian Electrotechnical
Institute facility in Istra. In many regions of Russia the climatology of the elec‑
trical processes
in the atmosphere, regional meteorological peculiarities of thun‑
derstorms and further developmnent of methods for modelling and forecasting
thunderstorm phenomena have been investigated. Several unique experimental
studies of high-energy processes in the atmosphere correlated with lightning
activity were performed. Discharges in the middle atmosphere were theoretical‑
ly analysed, and new methods for their detection were developed. A number of
studies were successfully performed at the Tatiana and Tatiana 2 micro-satellites;
interesting results were obtained at Chibis satellite, which had been aimed at the
study of high-energy phenomena in the atmosphere. RosHydroMet have been