Journal of the Meteorological Society of Japan. Ser. II
Online ISSN : 2186-9057
Print ISSN : 0026-1165
ISSN-L : 0026-1165
Volume 27 , Issue 3
Showing 1-5 articles out of 5 articles from the selected issue
  • Turbulence in the free Atmosphere 4th Report
    M. Shiotani, G. Yamamoto
    1949 Volume 27 Issue 3 Pages 67-73
    Published: 1949
    Released: February 05, 2009
    In this report, the scale of turbulence was discussed along the line of the statistical theory of turbulence of G. I. Taylor. Time correlation Rξ were calculated and forms of (Rξ-ξ) curves were shown. Spacial correlation _??_z were also calculated. Scale fo turbulence Rξ dξ is about 30 meters in the cases of strong wind and is about 3 meters in the cases of slow wind at a height of 60 meters. From the curves of Rξ, the spectral distributio of the turbulent energy were calculated according to the theory of G. I. Taylor. Brief discussions were done on the menthod of statistical analysis of the record of velocity fluctuations.
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  • M. Shiotani, G. Yamamoto
    1949 Volume 27 Issue 3 Pages 73-77
    Published: 1949
    Released: February 05, 2009
    The structure pf wind was investigated at Onohara plain, Kashima Gun, Ibaragi Prefecture. Five hot wire anemometers were equipped to the wooden tower of 15 meters high. Their heights were about 1m, 3m, 5.5m, 10m, and 15m respectively from the ground. Fluctuations of wind were obtained from the record of electromagnetic oscillograph, and characters of u'-fluctuations, intensity of turbulence, scale of turbulence and eddy viscosity were calculated from the records. The intensity of turbulence_??_ is smaller than 0.2 above a height of 5m, and increases downwars. Scale of turbulence and eddy viscosity increases. upwards. Their magnitudes are about 4 meters and 2×104 cm2/sec at 10 meters height.
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  • I. Imai
    1949 Volume 27 Issue 3 Pages 78-83
    Published: 1949
    Released: February 05, 2009
    Supercooled water clouds often contain minute snow crystals, 10_??_100μ in size, which are considered to be the incipient stages of growth. The author collected about 200 photomicrographs of those crystals at the observatories of Mt. Fuji and Mt. Ibuki, and investigated the relation between their crystal forms and the air temperatures at the time when observed. The columnar forms were always observed at the temperatures above -10°C, and the tabular forms below-9°C. The observed temperature ranges of various crystal forms are shown in the table. These results are nearly consistent with the case of artificial snow.
    The author concludes that all snow crystals are, at the first stage of its formation, perfect crystals of 10μ in size, which undergo different skeletal growth corresponding to the temperature, i, e. in the direction of principal axis above -10°C, and in the direction of secondary axes below -10°C. The temperature range of most rapid growth parallel to the secondary axes is -12.5_??_-15°C. This is by 1_??_2°C higher than that of dendritic form of artificial snow.
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  • Katsushige Sakata
    1949 Volume 27 Issue 3 Pages 84-87
    Published: 1949
    Released: February 05, 2009
    The author prepared a nomogram (Fig. 3) for calculating the dynamical magnification to evaluate the real amplitude of earth's motion from seismological records. It is consisted of two straight lines and one network, and only one operation on it is sufficient to attain the aim. In the nomogram, V; u, T0, T and W mean the fundamental magnification, damping ratio, proper period, of the seismograph, period of the earth's, motion and the dynamical magnification defined by respectively.
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  • H. Sekiya
    1949 Volume 27 Issue 3 Pages 88-98
    Published: 1949
    Released: February 05, 2009
    By the investigation of 89 waterspouts which occurred during the 23 years, from 1926 to 1947, we obtained the statistical results as follows:
    (1) The cause of occurrence were classified into types of cold front, warm front, high pressure area, frontal zone, convergent line, Taiwan depression and head thunderstorm.
    (2) The number of occurrence is maximum in September and minimum in April.
    (3) Waterspouts which were caused by cold fronts amount to 57% of all, and they mostly occur in the Japan Sea side and they were maximum in number in September.
    A typical pressure pattern of occurrence is that of cold front accompanying cyclones and others are those accompanying Siberian high pressures, as well as Manchurian, North or Middle China and Japan Sea high pressures, and local cold fronts of Boso peninsula. The number of occurrence shows a maximum in the afternoon. The number is small in the morning and in the evening.
    (4) Waterspouts caused by warm fronts are 17% of the whole number, and they occur only in the Pacific Ocean in the monthes of June to September. There are two types of pressure patterns of this case, the one accompanying typhoone and the otter accompanying typical fronts. The former occurs in any plac_??_ from Loochoo Islands to Kanto district, but the latter is limited only to areas west of Kii peninsula. (5) Waterspouts which occurred in the high pressure area were limited to the area to the south of Loochoo Islands and to Hokkaido. The former cases mostly occurred in the summer seasons and the latter cases in autumn. Time of occurrence is limited to the houre of afternoon excluding night time.
    Collecting the Data (surface observation, Pilot, Radiosonde) the author found, some interesting and remarkable facts as follows.
    (1) For the occurrence of waterspouts, it is necessary that sufficient energy of unconditional instability or discontinuity of wind in the where between 1, 000m to 2, 000m should exist in the atmosphere, but, it is not necessary that both of thse exist together.
    (2) Layer in which the waterspouts occur is very unstable and it disappears very easily.
    (3) Seasonal difference in strength of waterspouts is not recognized but the waterspouts which occur in high pressure area arc weaker than those that occur at the fronts. More detailed investigation about these remarks will be reported by the author in the near future.
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