Journal of the Meteorological Society of Japan. Ser. II
Online ISSN : 2186-9057
Print ISSN : 0026-1165
ISSN-L : 0026-1165
Volume 18 , Issue 3
Showing 1-8 articles out of 8 articles from the selected issue
  • K. Takahasi
    1940 Volume 18 Issue 3 Pages 77-80
    Published: 1940
    Released: February 05, 2009
    JOURNALS FREE ACCESS
    It is well known that a polar continental airmass becomes unstable when it travels over warm sea. The cloudy weather of Formosa and the snowfall on the coast of Japan Sea in winter are explained by such transformation of the air-mass which is brought by the monsoon from the Asiatic continent. In this paper, such transformation of the cold and dry air-mass by traveling over warm sea is numerically calculated by the help of adiabatic charts under the following assumptions.
    1) The temperature of sea water is constant.
    2) The process in the atmosphere is adiabatic.
    3) The air-mass has no vapour when it starts from the continent.
    4) The lower layer of the atmosphere becomes unstable up to some height by the heating from the sea, so that astrong convection is expected, and hence mixing ratio and equivalent potential temperature become constant in that layer.
    5) The amount of evaporation per unit time per unit area from the sea is given by dm/dt=A(E-e), where A is a constant, E maximum vapour tension at the temperature of the sea water, e vapour tension in the air.
    6) the amount of heat supply per unit time per unit area from the sea is given by dQ/dt=B(Ts-Ta).
    The results obtained are as follows.
    1) Clouds begin to form in the air-mass at a certain distance from the continent and the cloud height becomes lower and its thickness becomes larger as the air-mass travels over the sea.
    2) When the temperature difference between the air-mass and the sea water is large, clouds are easily formed and their thickness is large.
    3) The temperature of the air riese with the traveling, by the heating from the sea. However, the temperature difference between air and sea is comparatively large, say 6°C, even after a pretty long journey over the sea.
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  • H. Arakawa
    1940 Volume 18 Issue 3 Pages 81-84
    Published: 1940
    Released: February 05, 2009
    JOURNALS FREE ACCESS
    Die Luft erhält im ersten Falle, d. h. bei ihrer Verlagerung gegen wärmere Unterlage, allmählich den Charakter einer Kaltmasse; sie ist unten instabil, später setzt eine lebhafte Konvektion ein. Die Feuchtigkeit der Kaltmasse wird also bei der Verlagerung zum Äquator hin sehr rasch zunehmen. Die Strömung wird, besonders in den unteren Schichten, turbulent und böig; es kommt zur Bildung der Cunb-Wolken und zum Niederschlag.
    Im zweiten Falle, d. h. bei Verlagerung gegen kältere Unterlage, erhält die Luft den Charakter einer Warmluftmasse; sie ist unten stabil, und ihre Strömung ist laminar. Die Feuchtigkeit der Warmluftmasse ist daher sehr konservativ und bleibt bei der Verlagerung zum Pol hin nahezu konstant.
    Die mathematische Lösung des vorliegenden Problems würde ja auch eine Lösung der allgemeinen thermo-hydrodynamischen Grundgleichungen bedeuten, die sehr schwierig ist. Bei meiner Grundgleichung habe ich aber kein Bedenken getragen, einen einfacheren Ausdruck zu benutzen, welcher für die Temperatur T als die analytische Bedingung gelten soll, wo t die Zeit, z die Höhe und k den Koeffizienten der Temperaturleitfähigkeit bedeutet. Wir setzen zunächst eine horizontale, geradlinige, unbeschleunigte Bewegung υx voraus und nehmen an, dass alle Bahnen einander parallel verlaufen. Dann wird ∂T/∂t=0 und die Gleichung lautet: Nimmt man an, dass die Bodentemperatur sich in Horizontalen stetig ändert und nach einer Seite hin zu- oder abnimmt, dass aber wieder die Temperatur der Luftschicht am Anfangspunkt bis zu ihrer Höhe T=T0z ist, dann ist die Grundgleichung so zu integrieren, dass sie die Grundbedingungen fûr x=0 und z=0 erfüllen. Die wirkliche Berechnung vereinfacht sich sehr, wenn man von dem Umstande Gebrauch macht, dass die Neigung der Isobaren gegen den Horizont sehr gering ist. Günstig ist darn vor allem, dass die Adiabatentafeln zur Berechnung des Kondensationsdruckes verwendet wird. Richardson1) verwendet statt der z-Koordinate den Druck p, wobei wird und, wenn K, k und die Dichte ρ mit der Höhe konstant angenommen werden, K=3g2 ist. Man kann die Temperatur der Luftschicht am Anfangspunkt bis zu ihrer Höhe T=T0-β(p0-p) setzen, wo T0 die Temperatur im Niveau bei gleichbleibendem Druck p=p0 ist, und β der vertikale Temperaturgradient. Aus dieser Berechnung folgt die Beziehung
    Setzen wir zur Abkürzung μ=(p0-p)√υx/2√Kx, so lautet die Lösung bedeutet.
    Verstehen wir unter s die Wasserdampfmenge, so gibt uns dasselbe K die Diffusion der Dampfmenge. Aus einer Berechnung, die jener der Wärmeleitung ganz ähnlich ist, folgt die Beziehung Aus der Gleichung gewinnen wir in analoger Weise die Lösung Im folgenden sollen einige numerische Beispiele angeführt werden. Gegeben sei Die Temperatur- und Feuchtigkeitsunterschiede für die Höhe sind aus Abb. 1 und 2 ersichtlich. Bei Verlagerung gegen wärmere Unterlage erhält die Luft allmählich den Charakter einer Kaltmasse. Ist im Anfangszustand die schichtung stabil, so nimmt die potentielle Temperatur ebenso wie die pseudopotentielle Temperatur mit der Höhe zu. Nach der Verlagerung gegen wärmere Unterlage wird die Luftmasse instabil. Je grösser der Temperaturgradient in den Horizontalen ist, desto grösser ist die Entstabilisierungswirkung.
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  • S. Honma
    1940 Volume 18 Issue 3 Pages 84-90
    Published: 1940
    Released: February 05, 2009
    JOURNALS FREE ACCESS
    The transversal wave propagated along the surface of a semi-infinitely elastic body, the elasticity of which increases linearly with the depth, is discussed. The effect of the variation of density is also examined. The mathematical treatment is reduced to find a function φ(z) which satisfies
    Putting kz=x, kd=h and where b0 means the value of √μ/ρ at the surface, we may assume the following solution: The path of integration K is shown in Fig. 1.
    The dispersion curve is determined by h and α which are connected with each other by a relation: It is easily verified that α must be larger than unity, which is to be consistent with (1).
    When h is comparatively small, it is convenient to transform (1) into the following form: and τ exceeds unity so slightly as to make e-hN negligibly small. Assuming various values of α for an assigned value of h and operating the integration numerically, we may obtain the value of α wanted.
    The white circles on the dispersion curve in Fig. 3 show the values obtained by this method. whereas the black ones are those obtained by the following method.
    If h is comparatively large and so α becomes also large, we may obtain the integration (1) in special cases when α is an integer, and the corresponding value of h may be calculated. Therefore we may ees the tendency of the dispersion curve. In the limit of L (wave length) →0, dV/dL tends to ∞.
    Finally, it is verified that, assuming the distribution of the density in the form ρ=r+sz (r and s being constants), the conditions of existence of surface wave are r>O and. Under these conditions, the property of dispersion is characterised by the equations and the numerical relation between α and h coincides with that in the case of constant density. (As for the notation, refer to the equations (18)_??_(22).)
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  • K. Hiyama
    1940 Volume 18 Issue 3 Pages 90-97
    Published: 1940
    Released: February 05, 2009
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    Many authors dealt with the investigations of the sea surface temperature, for the purpose of obtaining the relation between the cool summer in North Japan and the cool temperature of the sea surface. In this paper, by investigating the data of the routine oceanographical observations made in the last three (or two) years, Sept. 1936-Aug. 1939 (1938), the author obtained some statistical results as follows.
    1. In summer season, May-Sept., at the coastal A station there are generally found warmer temperatures than those at stations five (B) and ten miles (C) off the coast, while in winter their relationship is reversed, Oct. and April being the period of interchange. An exception to this rule is found with the surface layer in which water is almost warmer off-shore (B and C) than at the coast throughout the year except June.
    2. The modes of the annual variation of water temperature, especially that of the phase lag varies with the depth.
    3. We could recognize the so-called “Tugaru Warm Current” at B and C stations in summer without respect to salinity.
    4. Under the weather types such as so-called “summer type” as well as “high area type”, the water temperature has tendency to rise or is higher than normal temperature at the season and under the type of “low area”, of “line of discontinuity” and of the “Okhotsk high”, the sea temperature has a tendency of gradual descent or is lower than the normal.
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  • T. Kitaoka, T. Haraguti
    1940 Volume 18 Issue 3 Pages 97-106
    Published: 1940
    Released: February 05, 2009
    JOURNALS FREE ACCESS
    Wooden houses were experimentally burned in the city of Hukuoka on 14 Oct. 1939, and on that occasion the radiation from them was measured with an instrument specially designed for long wave radiations. As shown in Fig. 1, A and B are thermometers of the same construction, sensitive parts of the former being blackened by the smoke of camphor. The A-thermometer is exposed to the radiator, whose intensity of radiation is to be measured, through a cylindrical tube a, and the B-thermometer is wrapped in a brass cylinderb, the inside of. which is covered with a layer of asbestos, for the purpose of being protected from all kinds of radiation coming into its sensitive parts.
    To be able to neglect the effect of change of air temperature and to simplify the principle of this instrument, currents of air are sended through the sensitive parts of the thermometers, as constantly as possible, from holes in the lower ends of b and c to those in the upper ends of them.
    The constant of this instrument, necessary to calculate the intensity of radiation by means of the temperature difference between the two thermometers, was determined by observing the solar radiation with this and a silver-disc pyrheliometer at the same time.
    The results of observations are shown in Fig. 6 and Table 1. These results enabled us to estimate the maximum temperature of a part of wail, toward which the tube of this apparatus was pointed, and which would be about the center of front wall. It was 895°C at the first fire, when a one-storied house was burned, 1081°C at the second fire, when a two-storied house built as a common type of Japanese residence was burned, and 808°C at the third, when a two-storied house specially built as to be protected from fire was burned.
    The proportions of the amounts of heat energy emitted by the process of radiation only to the total amounts of heat sended out from the houses are perhaps 17% to 31% at the first fire, 22% to 34% at the second, and 19% to 25% at the third.
    It is shown that these results of our observation are probable, comparing the calculated values with those obtained formerly by other authors.
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  • Y. Ogura
    1940 Volume 18 Issue 3 Pages 107-111
    Published: 1940
    Released: February 05, 2009
    JOURNALS FREE ACCESS
    The results are as follows:
    1. The concentrations of nitrite, nitrate and sulphate increase in winter and decrease in summer; on the contrary, there was no remarkable annual variation in pH and ammonia.
    2. There are found no distinct relations of the wind direction and the path of cyclone to the chemical composition of rain water.
    3. The chloride content increases with the wind velocity, but on the other hand, other components show their maximum of concentration at the wind velocity of 2-5m/s.
    4. The rate of pollution decreasses with the amount of rainfall except the rate of chloride, which was almost independent of the latter.
    5. The mean value of nitrite content of the rain accompanied by thunder was about twice as much as that of the ordinary rain.
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  • K. Uwai
    1940 Volume 18 Issue 3 Pages 112-114
    Published: 1940
    Released: February 05, 2009
    JOURNALS FREE ACCESS
    In this paper, the following equations of motion with their boundary conditions were used for a theoretical explanation of the surface wind:
    where r and s being the coefficients of slipping, v1 and v2 the coefficients of eddy viscosity and u0 and υ0 the velocity components of the surface wind. The results obtained from the calculation by selecting the proper values of r, s, v1 and v2 were found to agree well with the observations made at various stations.
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  • K. Hasimoto
    1940 Volume 18 Issue 3 Pages 114-115
    Published: 1940
    Released: February 05, 2009
    JOURNALS FREE ACCESS
    The author of the present paper investigated the small oscillations of temperature and humidity using the thermogram and hygrogram obtained at the Miyakozima Meteorological Station. The small oscillation of temperature begins to appear at sunrise and disappears in night hours, and its frequency of appearance shows maximum at about 12-14h. The frequency of small oscillation of humidity is analogous to that of temperature, and when it is windy it appears also in night hours. Further, it is found that these small oscillations are closely related to the solar radiation and the wind velocity.
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