The high sensitive quick running magnetograph records the sudden change of magnetic field strength at the instant of lightning discharge. The author of the present paper solved the equation of motion of the suspended magnet of the magnetometer with a control magnet, with the initial velocity determined by the sudden change of magnetic field at the instant of lightning discharge. The relation between the maximum swing Φ of the magnet and the electric quantity Q of the discharge is expressed by where M is the magnetic moment of the suspended magnet, D the damping coefficient of the moving system, K the constant determined by the position and length of the discharge. M, D and other constants have been determined for our magnetometer. The author has examined the horizontal force magnetogram of Aug. 26th 1934. On this day the thunderstorm associated by a discontinuity-line swept over Toyohara, Sakhalin, from SW to NE, and _??_used 46 cases of the sudden change of magnetic field. When the thunder heard from west quadrant almost all the change is negative. On the contrary when the thunder heard from east most change is positive. From this we can see this thundercloud has the polarity of C. T. R. Wilson's type. We have five cases of which both the lightning and thunder were observed. The electric quantity of the lightning discharge was calculated from maximum swing of the suspended magnet, assuming plausiblly the position and length of the discharge in several ways, knowing the distance of the discharge by the time interval of lightning and thunder. The result was that the electric quantity of the discharge ranged from 20-30 to 200-300 coulombs. This is several times larger than that observed by C. T. R. Wilson in England, and B. F. J. Schonland and J. Craib in south Africa with the capillary electrometer.
In the first paper, the present author has attacked the same problem using the data given in A. Schmidt's paper, but some important points were remained untouched there. These point are such as those of the assumption of the variation of the magnetic force with height, the error accompanied by the calculation and the recalculation based on the new and precise data of the magnetic force. In this paper these important problems are discussed with an additional notice on the physical interpretation of the current. (a) In the first paper, the present author adopted the following expression after the wireless research made by Appleton and Builder: This expression is the same as that which shows the distribution of the magnetic force near the earth's surface when a magnet was placed at the centre of the earth. Then the values of the magnetic force on the earth's surface calculated by the above assumption are considerably different from the observed ones. The expression which characterizes, without serious error, the distribution of the magnetic force on the earth's surface was already given by Gauss and others. This expression may afford us a criterion of the expression used in the first paper. According to Gauss, the components of the magnetic force are expressed by If we put r=R+h, we have The observation shows us that the second term of the right hand side of this expression is of the order of 1/10 or so as compared with the first term. This means that The expression (1) is able to be used if h/R is of the order of 1/10, namely if we consider h to be of the order of several hundred kilometers. Therefore the horizontal electric current calculated in the first paper is the average current in the region extending from the earth's surface to the upper atmosphere of several hundred kilometers of height, generally including the ionosphere. (b) The values of the magnetic force adopted in the first paper were based on those given in A. Schmidt's paper. Therefore the original value may have a considerable error of 100γ or so. Thus the average value _??_0 or _??_0 obtained by the graphical method will be accompanied by the error of 500γ or so. Thus the expressions 2α_??_0+Z0A-Z0B and 2 sin θβ_??_0+Z0A'-Z0B', each of them is of the order of 1, 000γ, will have, the error less than 500γ. Therefore the calculated value of the horizontal electric current may generally lie out of the error. (c) The above discussions show us that the treatment in the first paper is not meaningless. Hence the author recalculated the horizontal current according to the data given by the magnetic surveying in 1922. In this paper the average values as to the latitude were calculated with the following result. The horizontal electric currents flow generally to the direction of the east and west as is tabulated in Table 1 and schematically given in Fig. 2. (pp. 61, 62.) The comparison of the current calculated from the data given in A. Schmidt's paper with those obtained in 1922 is graphed in Fig. 1, showing that the average features of the current are very similar. (d) It is concluded that the current is directed to east in the northern part than 30°N and in the region between the equator and 50°S. In the other part of the earth the current flows westwardly. The intensity of the current is of the order of 1amp/km2 and it is somewhat great at the polar caps. As in the upper atmosphere there exist the ionosphere with considerably deep distribution, the current of the same order of the above calculated value will be flowing in the ionosphere.
In the present paper, is made a theoretical discussion, based on W. Ekman's theory of drift current, on the direction of the general current near the bottom of shallow seas or bays produced by prevailing winds. Two special cases were fully discussed, viz. (I) The case of an enclosed sea of uniform depth, d'. Considering that a steady wind is blowing everywhere with the same strength horizontally along the positive direction of y-axis, the x- and y-components of the current produced thereby were formulated. The direction of the bottom current upon which the transport of sand particles on the bottom of the sea chiefly depends, is given by the expression tgα=A/B, in which where α is the angle between the direction in which the prevailing wind is blowing and that of the bottom current, measured clockwise starting from the former to the latter, T is the tangential stress of the wind, D' is the depth of frictional _??_nfluence, a=π/D', γx and γy are the slope angles of the sea-surface in the directions of x and y respectively, ρ is the density of sea water, g the acceleration due to gravity. α was computed for va_??_ious values of depth, d', and it was found that α gradually increases with the depth, d', but that it does not exceed 45° so long as d' does not exceed the depth of frictional influence. Thus, it follows that the mathematical expression representing the effect of prevailing winds may be written in the form F (γ) cos (θ-θ0+α). Since, however, α is small and negligible if d' does not exceed half the depth of frictional influence, we may use the expression F (γ) cos (θ-θ0) introduced before by the present author, instead of F (γ) cos (θ-θ0+α), for most practical purposes at least for the first approximation. (II) The case of a sea of uniform depth, d', with a straight coast. Considering that a steady and uniform wind is blowing horizontally along the positive direction of y-axis, the x- and y- components of the current produced thereby were formulated. The direction of the bottom current was found to be given by the expression tg (2π-β)=A/B, in which where β is the angle between the direction in which the wind is blowing and that of the bottom current, measured counterclockwise starting from the former to the latter. β was computed for various values of d' and θ-θ0, θ-θ0 being the angle between the direction of the prevailing winds and that of the coast line. Thus, the mathematical expression representing the effect of prevailing winds may be written in the form F (γ) cos (θ-θ0+π-β). Since, however, as in the case (I), (π-β) is not large if the depth of the sea is shallow and it is almost negligible if d' is less than half the depth of frictional influence, the value of F (γ) cos (θ-θ0+π-β) does not much differ from that of F (γ) cos (θ-θ0), and we may use the latter expression for practical purposes at least for the first approximation. It was further suggested that the above theory may be applied to some extent to the case of a peninsula. Some actual examples which seem to justify the above theory were found. A more detailed discussion will appear in a future number of the “Geophysical Magazine.”
The air current caused by the obstraction of Mt. Fuji will be shown by the vertical and horizontal diagrams of Mt. Fuji in Fig. 1 & 2, These pictures relate about the air currents adjacent to Mt. Fuji, how they make their way along the mountain side and they produce mountain cloud. The cloud is generated by the upward air urrent along the windward mountain slope and the counter current induced by the vortices in leeward side of mountain. The cloud form changes according to the wind volocity, and the cloud location is due to the distribution of humidity. The figures of cloud are studied by stereoscopic photographs and cinematographs. Fig. 3 & 4 are the cloud forms by vortex motion, the wind is stronger in Fig. 4 than in Fig. 3. Fig. 5 shows the figure of cap cloud. Fig. 6 & 7 are the kind of lenticular cloud and Fig. 7 shows the figure of vortex motion under the cloud. I suppose such clouds to be generated by the upheaval of air caused by vortex motion in leeward side of the mountain. The cloud figure of this kind sometimes resembles like a wing of bird shown by Fig. 6. I think such special cloud form should be named “wing cloud”
The “pull-push” distribution of initial motion of P-wave no shallow earthquake were studied by Mrs. Kawasumi and Minakami, taking into account the effect of Moho_??_ovi_??_i_??_'s layer. But, on the other hand, Dr. Wadati, and others denied the existence of such a layer and in a depth corresponding to it, velocities of scismic waves become nearly constant. The present author has calculated the distribution of the amplitudes of initial motion in the latter case with the following results:- 1. The distance corresponding to the radius of “Inflexion c'rcle” in the former case, can be com_??_etely explained by the latter and the shape of nodal line is slightly different from the former. 2. The calculated distribution of the amplitude of initial motion is in good agreement with the observed fact. We have calculated the vertical angle of nodal cone and the displacement near the epicenter in some shallow earthquakes.
It is frequently observed that in the day time the gradual changes of air temperature in the lower atmosphere are frequently attended by some remarkable, small fluctuations, and these fluctuations occur only in the fine weather under clear sky or under the sky with small amount of cloud. The present author studied these phenomena as observed by means of a bimetallic thermograph made by the Hasegawa Instrument company. As it was observed that these phenomena did not appear in the rainy weather and in the night, they may be attributed to the thermal fluctuations caused by the vortex-like turbulences produced by the insolation.
In this paper is given the author's statistical studies on the wave clouds observed at Kumagaya during the last 12 years. He treated the following problems with some applications to the weather forecasting: a) Time of appearance of the wave cloud and precipitation. b) Direction of the wave clouds and precipitation. c) Classification of the wave clouds and precipitation.