  The synthesis of isotopes is possible under conditions of power electric
discharge in the atmosphere. Knowledge of the radioactive 14C yield under flash
conditions (as additional channel of 14C production relative to the main -
cosmogenic one) is important for radiocarbon analysis. It is proposed the gross
model for evaluation of the upper limit of the 14C yield, which creation was
simulated for the altitudes up to 15 km. It is presented the results for yield
of radioactive isotope 41Ar which synthesis goes along with 14C creation under
thunderstorm conditions. It was obtained that the possible thunderstorm
mechanisms of 14C creation cannot compete with cosmogenic production.
