Recent observational data of electric conductivity over the ground are considered in order to investigate the electrode effect. On the basis of our numerical model, physical parameters corre?ponding to the experimental conditions are discussed. We had three types of pattern of observational data; 95.4%, 2.0%, and 2.6% of the data could correspond to the strong vertical mixing condition, the weak vertical mixing condition, and the weak vertical mixing condition with the larger ionization rate at the ground level, respectively.