Geoscience Reference
In-Depth Information
Fig. 5.22
Dependence of electric field of cloud on ground (
a
) and current in the lightning
channel (
b
)
a
b
n
e
, cm
−
3
−
E/E
cr
2
.
10
5
1
1
.
10
5
0
100
0
100
10
50
4
h, km
8
6
50
h, km
t-t
o
, ms
4
t-t
o
, ms
8
2
0
0
0
Fig. 5.23
Ionization in the zone of electric field overcriticality: electron concentration (
a
); electric
field (
b
)
fills all the overcriticality zone (see Fig.
5.16
). Luminosity of the ionization area,
caused by the excitation of molecules by hot electrons, takes place if the electric
field is comparable with the critical one and if the electron temperature, dependent
on parameter
E/N
, is sufficient for the excitation of molecules. It is natural to assume
that the intensity of radiation is proportional to the specific power of its ohm heating.
The integration over the layer depth gives dependence, from which follows that the
luminescence precedes only during the development of the avalanche and stops at
its arrival at the border of the overcritical area. This time has a value of about 1 ms.
The luminosity of the ionization area at the altitude of 70-90 km, arising during
the thunderstorm at a duration of about 1 ms, is associated with the observations of
“elves.”
