[in Japanese]

View full abstract

A simple, preliminary experiment on the effect of rotation on convective motion has been carried out by the method of rotating cylinder convection. Two different regimes of motion, i.e., mushroom regime and tornado regime motion, have been observed. By increasing the rotation (decreasing the Rossby number), the approaching transition of the mushroom regime to the tornado regime motion has been shown by means of two series of photographs.

View full abstract

[in Japanese]

View full abstract

This report describes the course and results of the research into the current methods of improved measurement of the water vapour content in the atmosphere.
A general survey and discussion of several kinds of hygrometers are presented in Chapter (1). On the basis of this survey and practical considerations, the merits and defects of moisture measuring elements such as the dew-point hygrometer, hair hygrometer, electric hygrometer, etc. are discussed and presented separately.
Subsequent chapters discuss the practical problems involved in the design, construction and characteristics of each hygrometer and show the experimental results of the high performance moisture elements developed by the author.
In the dew-point measuring method described in Chapter (2), particular emphasis is placed on the obtaining of a simpler method developed so as to be more easily available for meteorological and industrial practice. In the first place, some questionable points with regard to the fundamental conception proposed by Regnault in 1855 are pointed out. The operating principles and the design of an improved, automatic dew-point hygro meter for laboratory or field use are described. The instrument makes use of the photo-electric detection of the condensate on a cooled, polished mirror with a simpler refrigerating system and a heat-control system. In order to investigate what unfavourable factors affect the measuring accuracy, a microscopic study on the behaviour of the condensate on the cooled mirror is made.
The experimental results on the phase transition and the aggregation of the condensate on the mirror are also shown. Besides, the application to aerological observations and the method to improve the measuring accuracy are presented. The experimental results on the improved hair hygrometers are described in Chapter (3), which owe a great deal to the efforts hitherto done to clarify and improve the inherent properties of the ordinary hair, such as the lowering of the response to changes in humidity at temperatures below 0°C, the hysteresis effect, etc. The characteristics of hairs treated with various mechanical and chemical procedures, such as temperature coefficient, lag characteristics and aging effect, are presented, as compared with those of the ordinary hairs and in the light of the microscopic study on the surface and cross-section structure of the treated or ordinary hair. As its application for ground observation, a remote-recording type of hair hygrometer operating under a constant load is also shown. The measuring accuracy is discussed with reference to the interesting results of several comparative flight tests with other elements such as the electrolytic hygrometer used in American radiosondes and the electronic dew-point hygrometer described in Chapter (2).
Chapter (4) minutely describes the construction, design, and characteristics of the electrolytic and the carbon hygrometer. The manufuracting processes of various kinds of moisture-sensitive films used in humidity elements are described, and, then, the experimental results on their humidity characteristics are presented synthetically. The method of protecting the elements from the running effect of the moisture absorbent embedded in its moisture sensitive film, and the aging effect, both of which have already been pointed out as the main defects inherent in these measuring methods, is discussed.
At the end of each chapter, some conclusions on the characteristics, measuring accuracy and the limiting abilities inherent in each hygrometer are shown. Several problems to be considered and solved in future work are suggested on the basis of these conclusions.

View full abstract

The mean state of the axis of the Kuroshio shows a sine wave, with a wave length of about 1000 km. This length corresponds to the one between the Ryûkyû and Izu submarine ridges, and on the ridges the axis shows little fluctuation of path. And as the speed of the Kuroshio becomes weak, the amplitude of the trough of the wavy meander of the Enshismada becomes large, or the cold water region grows up. The period of this fluctuation is about 5 years or so, and the period of the western mass transport by the wind stress over the North Pacific is also of such a magnitude.
The phenomena of the meander of the Kuroshio current on such a scale demand the eddy diffusivity to be of the order of the magnitude of 10⁷∼10⁸cm²sec^-1.
The statistical predication of the path of the Kuroshio can not be done, for the positions of the axis have no significant correlations to each other.

View full abstract

An examination on the distribution of air stream velocity was carried out in a chamber which was constructed for the measurement of the mobility spectrum of atmospheric ions.
With the aid of photograp hy of streaks and puffs of cigarette smoke introduced into the air stream, velocity distribution has been determined.
In the range of air flow rate between about 4 l/sec and 9 l/sec, laminar flow was obtained without altering its velocity distribution over the cross section through the whole range of the chamber.

View full abstract

A new optical method for the determination of the aerosol size distribution using the measurement of the solar radiation is presented.The method is as follows:
The atmospheric aerosol particles are separated into finite discrete groups according to their size. Then the total spectral extinction (scattering) coefficient for solar radiation due to the atmospheric aerosol particles is expressed by the summation of each spectral extinction (scattering) coefficient due to these discrete groups of the aerosol particles. Thus the simultaneous linear equation containing the numbers of the aerosol particles in each group (the unknown quantities) which denote the total extinction (scattering) coefficients for solar radiation at various wavelength observed are obtained, then the numbers of the aerosol particles in each group, i.e. the aerosol size distribution are obtained by solving the above simultaneous equation. It is, however, troublesome to solve the above simultaneous equation one by one. So it is shown that the aerosol size distribution can be obtained by the easy and simple calculation if the inverse matrix of a matrix whose elements consist of the coefficients of the above simultaneous equation, i.e. the efficiency factors for scattering (extinction) of the aerosol particles in each group are calculated and tabulated.

View full abstract