Transient variations of secondary cosmic rays due to atmospheric electric field and evidence for pre-lightning particle acceleration

We present the data on short-term variations of the intensity of secondary cosmic rays during thunderstorm periods. The effect is studied separately for the soft (electrons) and hard (muons) components of cosmic rays, their intensities being correlated with the near-earth electric field using a second-order polynomial. It is shown that the linear and quadratic terms are dominant for the soft and hard components, respectively. In addition, some irregular enhancements of the soft component just before lightning discharges are observed giving evidence in favor of some particle acceleration process. They can be considered as an experimental confirmation of the runaway breakdown theory developed for the process of lightning initiation. (C) 2002 Elsevier Science B.V. All rights reserved.