Journal of the Meteorological Society of Japan. Ser. II
Online ISSN : 2186-9057
Print ISSN : 0026-1165
ISSN-L : 0026-1165
Volume 25, Issue 10-12
Displaying 1-4 of 4 articles from this issue
• Equations of Variation in the Field of Pressure
1948 Volume 25 Issue 10-12 Pages 109-119
Published: March 10, 1948
Released on J-STAGE: February 05, 2009
JOURNAL FREE ACCESS
1. From the equations of fluid motion, it may be thought that the fluid motion occurs as the result of existing pressure field.
There may be, however, another point of view such that the deformation of pressure field may be caused as the result of fluid motion.
In the atmosphere, for example, the pressure atz nearly equals to and so varies when the distribution of density (_??_) changes (as the result of at-mospheric motion). But there has been found no type of equation, which denotes the atmospheric motion from the latter point of view.
2. Equations of atmospheric motion of Navier-Stokes are:
where l is the Coriolis' parameter.
Using the Fourier's integral theorem, the solution, w≡u+iv (i denotes Fi), is expressed in an infinite series: where
This solution shows, of course only formaly, that the wind is composed of many components, as if each of which is caused as the result of variation in the pressure field. But, as cited above, this consideration is merely a formal one.
Expanding the solution and neglecting the small terms of higher order, we get the following equations: where
These - I should like to name “Equations of variation in the field of pressure.” - are completely the same in form as the equations of motion.
Solving these equations, we get G(≡ G1+iG2) as a function of wind velocity and its variations in an infinite series.
Neglecting the higher order delivatives, the equations of motion are deduced conversely.
• G. Yamamoto, M. Siotani
1948 Volume 25 Issue 10-12 Pages 120-132
Published: March 10, 1948
Released on J-STAGE: February 05, 2009
JOURNAL FREE ACCESS
Five hot wire anemometers were equipped on the steel tower of 50 meters high, at Waebasi broadcasting station. They were situated on the tower respectively at heights of 38, 41, 44, 47 and 50 meters from the surface of the earth. Wind fluctuations at these points were synchronously recorded on the electromagnetic oscillograph. These records were analysed to discuss the intensity and the scale of atmospheric turbulence and also the coefficient of eddy viscosity.
• H. Yagi
1948 Volume 25 Issue 10-12 Pages 132-141
Published: March 10, 1948
Released on J-STAGE: February 05, 2009
JOURNAL FREE ACCESS
The author showed in his previous paper, “Study on the Mechanisms of Rainfall, ” that a steep and high boundary of air mass is most esential for rainfall.
In the present paper it will be shown by an example of tropical cyclone produced off the south-east of Formosa that a high-wall is most important also for the genesis and development of a tropical cyclone. As a result of the above fact it is shown that the cyclogenesis is decided by a high wall which extends to the upper troposphere and a thick solid-flow interposed on it, therefore it is regarded as a phenomenon of a wake benind an air mass obstacle.
Consequently the present theory is the vortex theory and at the same time the barrier theory.
But it is essentially different from Exner's barrier theory. His barrier is low, but the author's is so high, that it reaches the upper troposphere. As the cause producing a high wall is at a high level, probably the stratospheres it is not influenced by disturbances due to tta production or development of a cyclone, tnereiore it may be regarded as most important energy source for the development of a tropical cyclone.
When a high wall is interfered with by a thick solid flow which is gen_??_ally forced by a pressure wave, or thrust into a uniformly thick flow, a tropical cyclone will be formed behind an air mass obstacle.
According to the above theory the three air masses after Rodewald's theory ire not so much the cause as the result.
The present example, is that of a typhoon, therefore the author's theory can not be. extended to that of a cyclone without codification. According to the author's opinion, a cyclone appears as the result of combination of the pressure distribution of a high cyclone formed above the earth's surface layer (about 2 Km) with the horisontal density distribution in its layer.
Moreover the amalgamation of cyclones. can be explained by this theory.