<title>First observation of laser-triggered lightning</title>

Abstract

Laboratory and field experiments for laser triggered lightning were performed in order to induce so called triggered lightning, in which an electric leader initiates from tall objects on the ground to thunderclouds, using a plasma channel produced by CO<SUB>2</SUB> lasers and Nd lasers. Significant milestone was achieved in technological developments and verification of a scientific feasibility of the techniques such as determination of laser trigger timing which lead to laser triggered natural lightning. In the laboratory experiments technologies to produced long plasma channels and characteristics of discharge process induced by plasma channels were extensively investigated. In the field experiments developed are an automatic laser trigger system using an RF burst emission by a preliminary breakdown, methods to measure lightning path, thundercloud movement and field strength, and to make a continuous plasma channel at the top of the lightning tower which acts effectively for leader initiation.