Correlation of Charge Distribution Among Different Branches in a Natural Lightning Flash

Abstract

By analyzing the high-speed video camera images of a natural cloud-to-ground (CG) lightning flash, we attempt to employ the luminosity of descending stepped leader to infer the correlation of charge distribution among different branches. Observations are made using a high-speed video camera operated at 20000 frames/s. For a period of hundreds of microsecond before the return stroke, the correlation of charge density among different downward branches is acquired using the proposed algorithm. Besides, the charge simulation method (CSM) is adopted to get the charge density along the primary and secondary leader channels. Both the simulation and experiment results show that the charge density is highest at the leader tip and decreased approximately linear from the tip, indicating the effectiveness of our proposed model for retrieving the correlation of charge density among different branches. However, compared with the CSM results, the charge density calculated from the proposed algorithm is always changing. This characteristic should be taken into consideration in the research related to the lightning protection design.

Keywords

• CG lighting flash
• high-speed video camera images
• charge density
• charge simulation method