Electron temperature profile in the ionosphere has been measured with the K-10S-1 sounding rocket in both up and down legs. The electron temperature probe was installed on the top of payload with perpedicular to the spin axis, and the measurement of the electron temperature was so free from the interference with the attitude that the measured electron temperature has vey small dispersion and is quite reliable. The probe was flown up to the maximum altitude of about 720km in Aug. 28, 1965, from the Kagoshima Space Center. The measured electron temperture profile covers both bottom and top-sides of ionosphere. The result shows apparently a quite different profile between the up-leg and the downteg ones, especially at tae height of about 200km. However, a remarkablr similar profile among these two profiles can be found when the altitude scales are shifted about 60km each other, being such in up-leg at the lower level than in down-leg. Therefore, there seems to be a layer structure which inclines upward towards south-east direction. And the temperature decreases about 200°K from north-west to south-west. It seems that the layer structure of electron temperature is caused by that of the atmospheric constituent in the ionosphere, and the temperature difference between both legs is by the general tendency of latiudinal electron temperature distribution.

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A spheroid approximates the earth more accurately than does a sphere. Before analyzing the data over the surface of the earth by spherical harmonic series, we must correct them to the appropriate values on a true sphere. The change in the earth's radius and latitude, and in the direction of the vector components must be considered. The corrections have been applied here to values derived from existing analyses of the earth's magnetic field. The changes are significant, the largest being about 120γ in the g₃⁰ term.

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In this paper the charge separation in a thundercloud is discussed in relation to meteorological condition in it. Using the data obtained at Maebashi in 1962, 1963 and Utsunomiya in 1964, we have confirmed the distinct difference of the separation mechanism of local positive charge in thunder cloud from that of main charge. The height where the charge separation takes place is very much different for the two charges. In some cases the separation of the main charge is not accompanied by that of the local positive charge. When the cloud particles reach the height where the tempereture is roughly below -10°C, the main charge begins to separate. If downdraft, whose existence in thundercloud is confirmed indirectly, would obtain an appreciable strength, it could bring the heavy cloud particles down in the cloud. This would make the negative charge on the heavy particles to redistribute in the lower part of the cloud, probably resulting in Type I thunderstorm. If downdraft would not be strong, the storm would be Type II because of existence of wind shear, divergence, etc. in upper part of thundercloud. The duration of a cumulus stage so far measured, roughly amounted 45 minutes and that of mature plus dissipating stages 60 minutes.

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The effect of radioactive fallout upon the electrical conductivity of the lower atmosphere has been studied. The records of atmospheric conductivity which were made at the Geophysical Institute of Kyoto University in the period from 1961 to 1963 were compared with the records of the observation of fallout made in the same period at the Radiation Centre of Osaka Prefecture. The radioactive fallout, which originated from the large scale nuclear test explosion of 50 Mega ton class carried out by the U. S. S. R. at Novaya Zyemlya on October 30, 1961, caused a temporary increase in atmospheric conductivity up to the value twice as high as the normal value. The increase in conductivity was caused mainly by radiations from the dry fallout accumlated on the ground surface, which was estimated to have exceeded 250mμCi/m² at that time. On the other hand, radiations from the airborne nuclear debris, the concentration of which reached as high as 120μμCi/m³ at that time, were considered to have contributed little to the increase in conductivity.

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A comparison between a microscopic observation and magnetic examinations such as thermomagnetic curve, low-temperature characteristics and microscopic coercivity spectrum indicates that the magnetic stability of granites is primarily controlled by the grain size: stable granites abundantly possess extremely fine magnetite grains (grain size<5μ), whereas the unstable sample contains mostly coarse magnetite grain (grain size ≥50μ).
Magnetic characteristics of VRM of magnetite grain which is produced at relatively high temperatures are examined. VRM produced at higher temperature generally becomes magnetically harder. The increase rate of the magnetic hardness which is expressed as a recovery ratio in low-temperature demagnetization is maximum at about 200°C. However, the extrapolation of the experimental results to a geological condition indicates the recovery ratio (or the magnetic hardness) of VRM produced in a geological condition will be only several times that of IRM produced at room temperature. Therefore, the VRM of granites which must have been produced over a long period of time at relatively high temperatures may still be effectively erased by low-temperature demagnetization.

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A theory of free magneto-hydrodynamic oscillation, which gives rise to an S₁¹ type magnetic field, superposing on the fluid dynamo in the earth's core is advanced. It is proved that an S₁¹ field travelling eastwards relative to the core material is possible to exist. If the general westward drift of the core relative to the mantle is taken into account, the drift speed of the S₁¹ field relative to the mantle becomes slow though still westward. The speed thus estimated roughly agrees with the observed velocity for the drift of the equatorial component of the geomagnetic dipole.

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Non-steady state of a Herzenberg dynamo is studied by numerically solving non-linear integral equations. Although it is impossible to perform integrations over a long period of time, it turns out that a system of two similar spheres coupled with one another exhibits characteristic oscillations of the magnetic field as well as the angular velocity. Since the oscillation amplitude increases enormously as time goes on, it is concluded that a Herzenberg dynamo seems unstable for a small disturbance given to its steady state. No direct application of examined oscillations to a core problem is possible because integrations involved can be performed only for parameters which are very much different from those for the earth's core.

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