In this paper an attempt is made to explain the ionospheric F2 disturbances on the equatorial zone as the effect of the vertical drift of the electron caused by the electric field deduced from the disturbance-daily variation of the earth's magnetic field. The geomagnetic and the ionospheric data are those of Huancayo on the magnetic equator. The calculations of the disturbed variations are carried out for the individual ionospheric disturbances.
The results show that the calculated variations of the disturbances using the geomagnetic data are well in accordance with the observed ionospheric data, both in the magnitudes and in the characteristics of the variations. Therefore the ionospheric F2 disturbances near the magnetic equator can be interpreted as the effect of the vertical drift of the electron.

View full abstract

Simultaneous recording of electro-static field change, waveform of atmospheric, lightning flash photograph, were obtained with partial success during the the thunderstorm observation in summer 1955. The simultaneous records of electro-static field change, and waveform of atmospheric, each pair obtained at the moment of a cloud discharge, have been investigated and the possibilities have been suggested that some of the slow discharge processes in thundercloud will be mainly composed of corona discharges of various types between two charge centres in the cloud. Waveform of atmospheric, and lightning flash photograph, both relating to the same cloud discharge, have made it clear that the very rapid dart leader radiates the atmospheric with waveform of main discharge type. The directly correlated records of electro-static field change, and waveform of atmospheric, were also obtained concerning several ground discharges. This has made it possible to classify the recorded ground discharges into two types according as the discharge has α type stepped leader, or β type, following to the principle orginally reported by Schonland (1). The investigation indicates that no less than 60% of the recorded ground discharges has β type stepped leaders in this thunderstorm season. In spite of the insufficient number of available data at present it seems reasonable to consider that the greater part of the ground discharges in our country have β type stepped leaders.
It has also been made clear that the streamer emitting an outstanding single pulse, such as the return streamer of ground discharge, is always associated with secondary and somewhat slow discharge processes.

View full abstract

On the outcrop of the basalt lavas at Kawajiri-misaki (Cape Kawajiri), the present author has carried out a fairly continuous sampling of a number of test specimens from an area of one meter square of the outcrop belonging to entirely one rock block and has confirmed that the normal and the reverse natural remanent magnetism (N. R. M.) are found intermixed side by side in the very outcrop. On the other hand, the results of the thermo-magnetic analyses of the lava specimens suggest that the magnetic mineral responsible to the normal N. R. M. is predominantly a titanomagnetite of a phase having intermediate Curie point, whereas those to the reverse N. R. M, poly-phase having lower and higher Curie points than the intermediate. N. Kawai has recently proposed the idea that the self-reversal of remanent magnetism of rocks is possible to occur when the reverse magnetism of poly-phased titanomagnetites overcomes the normal of the pre-existing, single-phased, parent one of which the exsolution has produced the poly-phased ones. Both the field evidence showing the positional close intermixing of the normal and the reverse magnetizations in the same lavas and the results of the author's laboratory experiments to prove the exsolution do not seem to favour the geomagnetic field reversal hypothesis.

View full abstract