A method is proposed for the detection of the size distribution of atmospheric aerosols that have a radius from 5×10-7 to 5×10-6cm. To make a charge equilibrium of aerosols in which the fraction of charged particles depends on the size of the aerosols, the sample air containing the aerosols was irradiated with Po210 (α ray, approximately 100μ Ci) and the ion mobility distributions were obtained by the ion analyzer. The relation between the size (electrical mobility) and the charged fraction of the aerosols irradiated with Po210 was measured. From the result it was known that the Boltzmann distribution law was not valid for the small size. On the basis of this result, the ion mobility distribution was transferred to the size distribution of the particles. This irradiation method was applied to the measurement of diurnal variation in the size distribution in the urban atmosphere.
Nine expeditions have been carried out during the period 1968-71 to undertake measurements of the atmospheric electric parameters including nucleus concentration over the Pacific Ocean and the East China Sea. The chief objective of these expeditions has been to understand the behavior of the electrical state of the atmosphere as one moves from land to mid-ocean. The results have been analysed to see the influence of the land pollution on the measured parameters and have been discussed in detail how these parameters depend on the distance from shore, on the air stream patterns and on the time-histories of the air masses. In some favorable cases a clear dependence of the electric conductivity and the nucleus concentration on the distance from shore has been observed. The interpretation of the data showed that among the many possible factors which would influence the conductivity and nucleus concentration measurements, the age of the relevant air masses is vitally important when we . investigate the extension of the land pollution to the oceanic atmosphere. At the end, a comment on the self-consistency of the data collected during different expeditions at varying distances from shore is also described.
Trigonal ice crystals, ice crystals with the basal faces of a regular triangle, are formed by seeding I of using adiabatic cooling as well as by seeding II of using a very cold body. When ice crystals are made by the former seeding and are grown in free fall for about 200 seconds in a dense supercooled cloud, the production rate of trigonal ice crystals depends considerably on temperature of the cloud. At about -7°C it runs up to about 20%. Scalene hexagonal ice crystals, which are obtained in abundance at the same time as trigonal ice crystals, are inferred to be grown from trigonal ice crystals. Rhombic ice crystals, scalene pentagonal ice crystals and trigonal dendrites are also observed occasionally. These results mean that the growth directions <1120> and <1010> are the first and the second favourable directions respectively in the basal plane for the growth of ice crystals. In free fall growth, therefore, ice crystals having trigonal constructions seem to be obtained because growth toward<1010> initiate at the time of nucleation.
The growth of ice crystals has been studied in order to determine the effects upon crystal growth of electric fields of magnitudes similar to those found in the atmosphere. Needle type ice crystals were found to increase their growth rate by more than thirty times in electric fields of over 4.6×104Vm-1 while small hexagonal plate crystals were unaffected by the electric field. The observed phenomena were attributed to enhanced electric fields at the highly curved regions of the ice crystals.
Samples of snow and rain water were collected at a site on the coast of the Hokuriku district in February and March 1970. Quantitative analysis of minerals in the solid particles contained in each sample was carried out by X-ray method. The main source regions of these particles were inferred from the analyses of the mineral composition of the solid particles and trajectories of air masses. The results are summarized as follows : (1) Most of the solid particles in snow sample were found to be soil particles blown up from the upper drainage basin of Yellow River (Loess particles). (2) The origin of the solid particles in sleet sample was very similar to that of the solid particles in the snow sample. (3) Most of the mineral particles in rain sample were considered to be soil particles originated from the upper drainage basin of Yangtze River.
Some observations in the field of cloud physics and atmospheric electricity were carried out when the author was a member of the wintering party of the 9th Japanese Antarctic Research Expedition at Syowa Station, Antarctica throughout the whole year from February 1968 to January 1969. Especially, a simultaneous observation of electric charges on natural falling snow crystals, the shapes of snow crystals and electric field strength were selected from a view point of importance and interest of the charge generation in clouds. As a result, a very interesting phenomenon was found in which the electric polarity of snow crystals of dendrite, sector and plate was negative and the polarity of snow crystals of column, combination of bullets and side plane was positive. Taking into account that the temperature range of the growth of dendrite, sector and plate is roughly between -10°C and -20°C and that of the other three shapes of snow crystals are between -20°C and -35°C, it would be appropriate to assume a positive polarity of a thundercloud and other electrified clouds with solid precipitation particles. In other words, it may be considered that negative and positive charge centers in the cloud volume are located around the -15°C level and the -25°C to - 35°C level, respectively. These temperature ranges coincide with Takahashi's observation (1965) using an electric charge sonde, in which he reported that positive charged particles were observed at a temperature range between -18°C and -39°C and negative charged particles were present at a range between 0°C and -18°C.
Variations of excess carbon-14 injected into atmosphere by nuclear tests are analyzed during the second moratorium of atomic bomb tests. Regression equations are obtained from the time series data at different altitudes and latitudes. Vertical propagation speed of the phase of annual variation is estimated from phase difference at different altitudes. Downward propagation speed of 1.1 km/month has been obtained in the layer from 60, 000 to 40, 000 feet (18.3-12.2 km) at 72°N. At 33°N an upward propagation speed of 2.4 km/month is seen between 100, 000 and 90, 000 feet (30.5 and 27.4 km). Analyses of time series data of excess carbon-14 amount and temperature suggest that variations in carbon-14 amount with period of 1.5 to 2 months are caused by vertical motions. Some discussion is presented on variations in carbon-14 amount in comparison with ozone.
An analysis is made of the vertical structure of the Aleutian anticyclone in the upper stratosphere and its temporal variation during the winter season of 1971/72 with the aid of meteorological rocket and satellite observations. The rocket observation at Ryori (39.0°N, 141.8°E) indicates the alternating appearance of easterly and westerly winds in the middle and upper stratosphere over northern Japan with a time-scale of about one month. From the synoptic analysis of the Northern Hemisphere stratospheric circulation up to 1mb, it is found that the strong easterly wind over Japan is associated with the Aleutian anticyclone, the center of which is located to the north-west of Japan. Horizontal time-sections of geopotential height and temperature along 45°N indicate that the quasi-periodic variation of the east-west wind component as revealed by rocket observations is due to the spatial fluctuation of the anticyclone center in the east-west direction. The warm region associated with the wave-like disturbance can be traced at least up to the stratopause over Siberia, and as the result of inclusion of this warm region the zonally averaged temperature in the upper stratosphere and lower mesosphere in polar latitudes is found to be a few ten degrees higher than the climatological temperature based upon former observations over the western hemisphere only.