It is very important to know the nature of aerosol particles in the atmosphere which have sizes ranging from 10-7 to 10-5cm in radius. Particulary, it is interesting to measure the “charged fraction” of particles, i.e. the ratio of the charged particle concentration to the total concentration from the viewpoint of atmospheric electricity. In order to produce a charge equilibrium state of aerosols of a large ion range, sample air containing aerosol particles was irradiated by α-ray (210Po 200μCi) for a few seconds. By this method, the equilibrium state was quickly attained. For the purpose of determining whether the aerosols are in a charge equilibrium state or not, we measured the fraction of the charged particle oncentration to the total concentration, and compared that obtained with the natural aerosols sampled simultaneously with that brought to an equilibrium state by the above-mentioned method. It was found that the equilibrium state is established for a short time immediately before sunrise when the mospheric conditions are stable.
A quantitative analysis is made to investigate the mechanism of decaying of a tropical cyclone using the data of typhoon “Tilda” (6123). During the decaying stage of the typhoon, thermal structure of warm core at the upper layer is considerably modified. On the other hand the amount of released latent heat estimated for an air column enclosing the typhoon and extending from the surface to the top of the storm much decreases. So, this modification of the thermal field seems to be closely related to the change of activity of cumulonimbus convection within the typhoon region. It is the main purpose of the present analysis to clarify the relation between the change of the activity of convection within the typhoon region and that of warm core thermal field. For this purpose, we make a budget calculation of heat and water vapor, using the first law of thermodynamics and the continuity relation of water vapor respectively, and show that the convective transport of heat and water vapor, which has played an important role during the mature stage, weakens considerably as the typhoon decays. The later part of the analysis is devoted to determine the vertical distribution of liberation of latent heat. It is shown that the liberation of latent heat at the upper layer decreases remarkably as the thermal field is modified. This suggests that the diminution of high cumulonimbus towers which are the main source of released latent heat at the upper layer, plays an essential role on the destruction of the warm core thermal structure of the typhoon. Finally it is shown that the activity of high cumulonimbus towers is controlled by moisture supply in the lower layer.
A new method of integration of equations for the airstream over mountains as a threedimensional problem is presented. This method is applicable for any shape of mountain and for any airstream in which static stability, wind direction and velocity vary with height. The equation is solved numerically for specified cases and shows the mountain wave not only for lee-wave component but also for the flow in the neighbourhood of the disturbing hill.
In Japan, the seasonal variation of mortality from stroke (Int. List No. 330-334, Vascular lesions affecting central nervous system) has undergone a chronological change from the summer maximum late in the 19th century through the bimodal distribution to the current concentration in winter. In various contries abroad, it follows different curves peculiar to each of them, depending upon the degree of cultural progress. For instance, the winter concentration is much less prominent in Egypt than in the advanced countries, while on the other hand the Scandinavian countries as well as the United States indicates signs of the steady slowing-down of seasonal variation itself or gradual deseasonality. In this paper, a comparative study is made in the different forms of seasonal variation in mortality from stroke in England (including Wales), the City of New York, and the City of Tokyo (23 old wards), for which vital statistics are chronologically available. 1) In England, there was no summer peak whatever and the winter summit has got higher decade after decade, and the winter concentration now is conspicuous. 2) In the City of New York, little seasonal variation has been seen, and signs of the moderation of seasonal variation has been increasing since 1930. 3) In the City of Tokyo, representing the whole of Japan, the above-mentioned three stages of seasonal variation have been witnessed since early in the current century. In the high latitude areas (the Scandinavian countries) or the United States with a wide difference between heat and cold, or a very cold district like Hokkaido in Japan, where human living is neither possible nor comfortable without adequate environment control, the system of central heating or area heating has developed markedly. In the medium latitude countries or districts, where nearly no provision is necessary for artificial climate, the recent development of medical science and service has reduced the death rate in the hot season to the extent that old people have been on the steady gain in the age structure. And deaths among them occur most frequently in winter, bespeaking the winter concentration of mortality in these countries. It is to be emphasized that the seasonal variation of mortality, the winter concentration in particular, can be checked, if not eliminated, by artificial climate as seen in New York.
The two points spectral equations system of the 0-5th order cumulant approximation of the inviscid Burgers turbulence is formulated and the energy spectrum and the energy transfer are obtained as initial value problems. These results are compared with those from the 0-4th order cumulant approximation. The negative energy appears at larger wave number in the 0-5th approximation than in the 0-4th one, On the other hand, the appearance of the negative energy become rather earlier in time in the former than in the latter. The drastic appearances of the negative energy at the energy containing range in the 0-4th approximation are fairly removed in the 0-5th approximation. In the larger spectral range than the energy containing range, however, the conclusive results about the improvement of the approximation by the 0-5th approximation cannot be strictly introduced.
By making suspend the water drops over the vertical wind tunnel, we have the following results empirically (1) the number of the daughter droplets produced by breaking of the parent drop is not larger than a few in almost all cases (2) there are some relations between the frequencies of the wind tunnel turbulence and those of the vertical width of suspending water drops (3) the oscillations of suspending water drops become gradually complicated in their shapes with time.
Analyses of day to day variations of planetary waves and those of the mean zonal wind in the stratosphere are made throughout the period of five winters from 1963 to 1967 based on the gridpoint data of 30mb geopotential height together with the stratospheric synoptic charts. The monthly mean structure of planetary waves suggests the upward propagation of wave energy from the troposphere into the stratosphere. Day to day variations of the polar-night westerlies and those of the amplitude of wave number one at the 30-mb level show a periodicity of about two weeks, and a significant negative correlation is found between these two quantities. It is found that the wave amplification propagates upward when the mean zonal wind is relatively weak westerly. This suggests that the periodic variation of planetary waves is caused by the “time-dependent” energy propagation from the troposphere in response to the time change of the mean zonal wind in the stratosphere. Although the divergence of horizontal momentum transport due to the planetary waves is not always in good agreement with the time change of the polar-night westerlies, we may expect a possibility of the existence of an “index cycle” caused by the wave-zonal flow coupling for the stratospheric circulation.