Journal of the Meteorological Society of Japan. Ser. II
Online ISSN : 2186-9057
Print ISSN : 0026-1165
ISSN-L : 0026-1165
Volume 17 , Issue 3
Showing 1-6 articles out of 6 articles from the selected issue
  • K. Takahasi
    1939 Volume 17 Issue 3 Pages 77-86
    Published: March 05, 1939
    Released: February 05, 2009
    JOURNALS FREE ACCESS
    Three methods to predict air temperature were discussed. The first is the method of extrapolation, the second is that of air mass analysis and the last calculating method. These methods were applied to the daily air temperature prediction at Tokyo, and good results were obtained. The methods summarizedas follows.
    (1) The method of extrapolation. An assumption was made that diurnal change of the temperature is given by
    θ(t)=θ0+Af(t)
    where A is a constant depending on the weather, ƒ a certain definite function of one day period. And the assumption was proved to hold fairly well except in some special case, such as sharp discontinuity of the temperature exists in the atmosphere. Assuming these, the future temperatures are calculated from observced temperatures at two time points, and rapidly calculating method by graph was proposed.
    (2) The method of air mass analysis. Firstly it was shown that the change of the air temperature was accompanied with the change of vapour tension in the atmosphere, and nextly it was found that the night minimum temperature as well as maximum temperature was determined by the vapour tension and the weather. Hence, by predicting futrue weather and vapour tension, the future maximum and minimum temperature are calculated. The vapour tension is one of the conservative quantities of an air mass, and the prediction is comparatively easy.
    Further, theoretical consideration of the above method was made. The energy transfer at the immediate neigbourhood of the ground is expressed approximately by
    LA(emax-e=LA{e(T)-e}
    ={JsT4(0·474-0·075_??_)}
    where left hand side is the energy due to evaporation, the right hand side the energy due to solar and effective radiations. And it is easily concluded that the temperature is the function only of weather and vapour tension.
    (3) Calculating method. From the theoretical consideration of the diurnal variation of the temperature, the following equations are derived.
    δT=N_??_T4
    where ΔT is the rate of cooling in night, and
    δT_??_=Js/1+v/v0
    where ΔT' is the rate of heating in day time. And the constants in above equations at Tokyo were determined.
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  • K. Yakame
    1939 Volume 17 Issue 3 Pages 86-94
    Published: March 05, 1939
    Released: February 05, 2009
    JOURNALS FREE ACCESS
    This component anemometer consists of a Robinson's cup anemometer and a wind vane, as shown in the photograph. The arrangement for resolving the wind movements into longitudinal and latitudinal components is as follows.
    The motion of the wind vane is transmitted to the grooved cylindrical cam by means of a hollow shaft. An uniform revolution of the cam causes a simple harmonic motion to a roller in the direction of its axis. The roller is in frictional contact with the surface of a disk, fixed upon an axis which intersects the axis of the roller at right angles. The disk is rotated by means of gearing down from the anemometer, namely proportional to the wind velocity V. Let one roller touch at the center of the disk when the vane turns in the East and West direction, and an other roller, in the North and South direction. Then the former revolves by, that is the integration of the longitudinal component, where θ is the angle of the vane measured from the North direction. Similary the latter revolves by, that is the latitudinal component.
    Each revolution of these rollers causes a electrical contact and records N. S. E. or W. component to the recording or counting apparatus. Besides these there is a electrical contact set for recording the total wind range. Therefore these five elements of winds can be recorded electrically with six wires.
    By this instrument we obtain not only great facilities for the climatological purpose, but also we can get the vector mean direction and velocity of winds which are difficult to measure on the level land up to this time. Moreover we can find the degree of “turbulence” of winds from the ratio of the vector mean velocity and the velocity from total wind range.
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  • S. Sakuraba
    1939 Volume 17 Issue 3 Pages 95-101
    Published: March 05, 1939
    Released: February 05, 2009
    JOURNALS FREE ACCESS
    Recently H. Solberg developed the tidal theory and emphasized the great importance of vertical acceleration in dynamical theory of tide. The same con_??_ideration is applicable to the theory of elastic oscillation of an atmosphere. Generalizing Margules' theory the present author developed the mathematical theory of free oscillation of an atmosphere. The detailed numerical discussion will be reserved for the second paper. The special case of non-ro_??_ating earth reduces to Rayleigh's solution. But his formula (α=radius of the earth, c=Laplace's sound velocity) is incorrect and must be replaced by In case of m=1 or 2, large errors occur by applying Rayleigh's formula.
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  • H. Arakawa
    1939 Volume 17 Issue 3 Pages 101-103
    Published: March 05, 1939
    Released: February 05, 2009
    JOURNALS FREE ACCESS
    A set of maps representing the topography of condensation level in space and time during the period from the 1st to the 23rd of August, 1938, has been constructed. The materials used in the maps are obtained from surface observations of 70 or more stations. It can be tentatively inferred that thundery conditions will occur if the condensation level of surface air is lower than the level 700 mm Hg. (about 600-700 m height). The set of maps, Fig. 1 and 2, represents the topography over Kyusyu District on the 20th of August at 9h and 12h. It appears reasonable to suppose that the low condensation level was actually responsible for the severe thunderstorm on that day. Fig. 4 represents the topography on the 12th of August at 12h. An examination of Fig. 4 indicates that on that day would not have occured by the ascent of surface air, the condensation below a level of about 700 mm Hg. On that day the thunderstorm actually did not originate over Kyusyu. It is, of course, impossible to draw any definite conclusions from the maps on rainy days. On rainy days, even if conditions of low condensation level appear quite favourable for a thunderstorm, any thunderstorm may not actually happen.
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  • H. Futi
    1939 Volume 17 Issue 3 Pages 103-104
    Published: March 05, 1939
    Released: February 05, 2009
    JOURNALS FREE ACCESS
    By this “Radiosonde” the variation of temperature is measured by means of the variation of electrical capacity (wave length) in the main circuit with varying the ch_??_nge of lengths of mercury columns of the two small thermometers. (see Fig. 1 in the text.) For measuring the height and thickness of clouds black-bulb small thermometer is used and for the air temperature up to about 7000 meters ordinary small thermometer is used.
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  • S. Yamaguti
    1939 Volume 17 Issue 3 Pages 105-106
    Published: March 05, 1939
    Released: February 05, 2009
    JOURNALS FREE ACCESS
    The values of potential temperature factors K=(760/N)0.288 and (750/N)0.288 for intervals of one mm Hg from 779 to 50mm Hg have been calculated and tabulated for use in the computation of the potential temperature. The potential temperature is expressed in the following formula θ=T(760/N)0.288 and θ=T(750/N)0.288 where T the actual temperature in °A and N the pressure in mm Hg. The potential temperature, of which standard pressure being 760mm Hg or 1000mb (750mm), can be computed merely by multiplying the actual temperature in °A by the proper factor K found from the table.
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