  Previously, all studies in this area of atmospheric physics, namely,
avalanches of relativistic runaway electrons (RREA), were carried out without
taking into account the presence of hydrometeors in thunderclouds, which could
seriously affect the results and their correspondence to actually observed
natural phenomena. This article takes into account hydrometeors in clouds. In
this work, the distribution of RREA was simulated in GEANT4 was simulated
taking into account various concentrations of ice particles. Modeling showed
that accounting for the presence of hydrometeors cannot be simplified and
reduced to a change in the main substance. Two methods are considered -
modeling of volumetric hydrometeors as separate modeling objects and as a
simple change in the components of a whole substance (adding water to air with
a corresponding density). These methods show completely different results.
Modeling by volumes of hydrometeors shows a decrease in the length of the
avalanche by 20 %, on the other hand, when modeling with a modified material,
the length changed only by 1 %. This suddenly proves that hydrometeors should
be taken into account in research, as they can significantly change the growth
length of an avalanche in real thunderstorm condition.
