Abstract
The diurnal variation of atmospheric potential gradient at eight stations in the Japan archipelago was investigated and the following results were obtained.
1) Times of occurren c e of the maximum of diurnal and semidiurnal variation generally coincide with one another at stations of rural situation.
2) In larger cities the variation of the potential gradient is controlled mostly by the electrical conductivity of the lower stratum of the atmosphere.
3) In rural c onditions only the semi-diurnal component of the variation of the potential gradient is controlled by the conductivity of the lower atmosphere and the diurnal component is controlled by a cause in the upper atmosphere.
4) The time of occurrence of the maximum of diurnal component of potential gradient in the Japan archipelago is 21-23h, GMT.
5) The diurnal component of the potential gradient is composed of the unitary variation and the local time variation. The latter variation has a close relation with the character of weather around the station.
