Abstract
It is shown that the geomanetic pulsation is caused by hydromagnetic oscillation of the exosphere excited by solar charged corpuscles impinging on the earth as predicted by Störmer. Pc-type Pulsations are excited by auroral particles impinging on the 09h impact-zone, of which latitude is higher than the usual auroral zone and which gives rise to a second auroral zone as suggested by Nikolsky. Pt-tpye pulsations are excited by particles impinging on the 21h zone, corresponding to the usual auroral zone. The L. M. T. dependence of the occurrence-frequency of geomagnetic pulsations is well explained, assuming that the intensity of geomagnetic pulsations at a station will be lesser as it is more distant from the impact-zone. On the other hand, the G. M. T. control in the occurrence-frequency, as suggested by Troitskaya, is to be expected due to an inclination of the geomagnetic axis to the axis of rotation of the earth.
