Intensities of the solar radiation diffusely reflected and transmitted by turbid atmospheres are calculated taking into account the effects of plarization and inhomogeneous startification at wavelengths of 0.45μ and 0.70μ. The aerosols are presented by particles with a real index of refraction of 1.33 and with radii distributed according to the continental model compiled by Manson. The aerosol concentration as well as the mixing ratio of aerosols to air molecules varies with height. The proportion of aerosol to Rayleigh scattering is determined for each wavelength in the light of vertical profile proposed by Elterman. Three cases of the turbidity condition including pure Rayleigh atmosphere are considered in order to study the effects of changes of aerosol concentration. The ground is assumed to be represented by a Lambert surface. Typical results are presented by isophotes of the brightness or by intensity distributions in the principal plane. General tendency of the diffusely transmitted radiation is in good agreement with observations. Brief discussions are also made about the effect of polarization and of optical stratification upon the brightness distributions.
The degree of polarization of the radiation diffusely reflected and transmitted by a turbid atmosphere is calculated taking into account the effects of inhomogeneity of the atmosphere at wavelengths of 0.45μ and 0.70μ. The aerosols are presented by particles with refractive index of 1.33 and with radii according to the continental model compiled by Manson. The largest size of radius in this study, however, is taken to be 3.0μ. Three cases of the turbidity condition including pure Rayleigh scattering are considered. Dependence of polarization upon the solar zenith angle, surface albedo, wavelength and aerosol amount is presented. General results are in good agreement with observational data. Comparison between measured and theoretical values for the dispersion (i.e., wavelength dependence) of polarization suggests the value of refractive index of aerosols to be larger than 1.33.
Theory indicated that for surfaces with temperatures significantly different from that of the ambient air, net radiation measurements become increasingly less representative of surface conditions with increasing height above the surface. This effect of the intervening air layer between the net radiometer and the surface was found experimentally to create a 7% discrepancy between the net radiation measured at 50 cm above a dry, bare soil and that measured at 215 cm for the daylight hours. On a 24-hour basis the discrepancy amounted to 11% of the total net radiation. In this situation, true net radiation is obtained only at the surface.
Comparisons were made between the Z-R relationships which were obtained from the data taken at three elevations 3.4, 2.1 and 1.3 km above the sea level along the eastern slope of Mt. Fuji. The precipitation observed was considered as generated from clouds of the warm-rain type. Raindrops were sampled by using filter paper during two shower rains. The Z-R relationships at each elevation were as follows : Z=48 R1.11 (3.4km) Z=88 R1.28 (2.1km) Z=240 R1.48 (1.3km) The significance of the difference between the parameters was consistent with the tendency in the showers in Hawaii Island which was interpreted by Fujiwara (1967) through accretion and evaporation.
Calculations based on both the Marshall-Palmer distribution equation and the concentrations of solid and liquid hydrometeors compiled by Sartor (1967), have been made of the contributions made by precipitation particles of different sizes to the charging rate, the maximum volume charge density on precipitation and the precipitation current produced within a cloud when a precipitation mechanism of electrification is operating. It was found that at all stages during the growth of the cloud the dimensions of the precipitation particles which provide the major contribution to the electrification are small. For a precipitation rate of 10 mm hr-1 the primary contribution is made by particles of less than 0.1 cm diameter and even in immensely active clouds with a precipitation rate of 200 mm hr-1 the optimum diameter is below 0.2 cm. On the other hand, the diameter of precipitation particles which provide the major contribution to the radar echo intensity increases from 0.25 to 0.42 cm as the precipitation rate increases from 10 to 200 mm hr-1. Calculations showed that the values of precipitation current and volume charge density which several workers have shown to be essential requirements of a tenable theory of thunderstorm electrification can be achieved by a precipitation mechanism operating with a precipitation rate of only about 15 mm hr-1, which corresponds to a precipitation water content of around 0.8 gm m-3.
In order to study the falling velocity of ice crystals, the drag coefficients of circular cylinders and circular disks were measured by a model experimental method. The terminal velocities 0f falling models in various liquids were measured and the drag coefficient and Reynolds number were computed from the velocities. The result of the present model experiment was applicable to computation of the falling velocity of snow crystals. Therefore, it may be considered that the drag coefficient of the present experiment is applicable to computation of the falling velocity of ice crystals with using the mass or density and the dimension of them.
Observation of cloud condensation nuclei was carried out at Syowa Station (69°00'S, 39°35'E), Antarctica from the beginning of February to the end of December, 1968 using a chemical diffusion chamber. Supersaturation adopted were in five grades of 0, 0.05, 0.1, 0.5 and 1% at the same time. As a result the mean number concentrations of 0 and 1% supersaturations at the station were 3×102 and 8×102 particles per cm3, respectively. The maximum concentrations of 0 and 1% were 3×103 and 4×103, and in only one case 9×103 particles per cm3 at 1% was seen. The minimum concentrations of both supersaturations were nil, but in general they were approximately in an order of 1×102 particles at 1% supersaturation. The high concentrations were observed in the range of the wind direction from ESE to S and they were related to the wind direction rather than wind velocity. The spectra of the number concentration in the range from 0 to 1% supersaturations showed two distinct patterns. One showed nearly flat spectra, namely 2-3×103 and the other showed steep gradients of 1-5×102 and 2-4×103 particles per cm3 at 0 and 1% supersaturations, respectively. The nuclei spectra showing steep gradients were considered to be from a man-made source judging from the shapes of the spectra and by the wind directions at the station. The nuclei showing a flat pattern were surmized to be of an oceanic source. An examination of the washout effect of cloud condensation nuclei in "before", "during" and "after" solid precipitation was carried out. As a result, the value of the number concentration of cloud condensation nuclei in "during" precipitation was less approximately 30% than that of "before" precipitation, and the value of the concentration in "after" precipitation was greater 200% than that of "during" precipitation in both 0 and 1% supersaturations.
A set of quantitative experiments on the electrification of sand particles suggests that they become charged symmetrically on a statistical basis, conferring charge on any other material they contact in a preferential way. Impurity transfer from the sand particles to other materials may also take place and there is some evidence that charging may partly be caused by pyro-electric effects.
As a continuation of previous studies (Yamasaki, 1969; Ooyama, 1971), the properties of wave disturbances superimposed upon zonal current in a conditionally unstable model tropics are studied by solving linearized primitive equations on the spherical coordinates. The effect of moist convection is incorporated by the use of the assumption that non-adiabatic heating due to convective clouds is specified by the horizontal convergence in the boundary layer, as Ooyama (1964) proposed in the study of tropical cyclones. In the absence of zonal current, surface friction and heat release, the model includes barotropic Rossby mode discussed by Haurwitz (1940b) in addition to baroclinic Rossby mode, gravity mode and Kelvin mode discussed by Matsuno (1966). It is found that the Haurwitz type waves of the lower meridional modes (n=0, 1) become unstable when surface friction, heat release and vertical shear of a zonal current are incorporated. The preferred wavelength increases from about 2, 000 km to 6, 000 km with the increase in vertical shear. Comparisons with observations show that the lowest meridional mode (n=0) is similar to the equatorial easterly wave described by Palmer (1952) and that analyzed by Chang et al. (1970). Since frictional convergence is a maximum at latitudes where the absolute value of the Coriolis parameter is equal to the frequency of this wave relative to the basic zonal current (Holton et al., 1971; Yamasaki, 1971), the stability properties of this wave appears to be strongly controlled by heat release associated with the frictional convergence around this latitude. The properties of other kinds of unstable waves are also discussed briefly.
The ultra-long waves on the 500-mb level in the colder season, October to April, during 20 years were separated into transient and standing waves, and the synoptic and statistical behavior of transient waves were studied. The transient waves for the first and second harmonics at high latitudes move generally westward as has been shown by the author. The retrogression of transient waves persists very often during a few 5-day periods or more and large amplification of these waves occurs more frequently in low- than high-index states. Several pronounced developments and retrogressions of blocking waves coincided well with those of transient waves. Generally speaking, the westward speed of blocking waves and positive anomaly centers are slower than those of transient waves. When the ridge of a developed transient wave for the first or second harmonics, accompanied by a blocking wave, moves westward at high latitudes and approaches to a trough in the standing (25-day mean) field in a persistent and severe low-index situation, a new ridge or an already existing ridge is intensified upstream on the 500-mb level and extends northward. Then the northern part of this ridge is covered by extensive positive anomalies with large-scale cut-off lows or negative anomaly centers to the south. Thus a typical flow pattern, called "bridge blocking", is established. The bridge blocking occurs frequently in the Far East, Europe and North America and disappears as transient and blocking waves shift further westward. As the bridge blocking makes the regional zonal index much below normal, the persistent retrogressionof developed transient waves indicates the persistence and intensification of the present severe lowindex situations. The transient waves defined in the present study are ultra-long waves with a time scale of about a month and the transient waves for the first two harmonics at high latitudes, associated with blocking waves and bridge blockings, play an important role in the general circulation.