Concentrations of ice-nuclei active at temperatures of -13°C, -15°C and -20°C were observed with an ice-nucleus counter in Tokyo, Japan. The concentrations varied from day to day in a wide range. Generally, higher concentrations occurred on days when air came from the continent of Asia and low concentrations occurred when air came from the Pacific Ocean. Abnormally high concentrations were observed when air reached Japan from the arid regions of North China and Mongolia where heavy dust storms occurred in front of cold fronts. Although the ice nuclei concentration was low in maritime airmass, sometimes high values were observed. This was found to be associated with volcanic eruptions. Possibility of production of ice nuclei from sea-spray is also discussed. The ice-forming abilites of volcanic ash from ten active volcanoes in Japan, of dust (loess) particles from North China which fell in Japan, and of soil particles and stone meteorite were determined in laboratory. It is concluded that the principal active ice nuclei in the atmosphere are some kinds of soil particles (especially, clay minerals) blown up from arid regions and volcanic dust from active volcanoes.
In Section 3, wind speed in the vicinity of mountains is shown to be small. The role of Rocky mountains as a barrier to the mean eastward current is also made clear. A pattern of air flow over mountains in a vertical cross section along zonal direction is presented. The mean state of balance among the force due to pressure gradient, Coriolis force and the force by Reynolds stress and friction is presented in Section 4. The influence of friction on mean air flow is evident near the lower boundary of the atmosphere. The ratio of mean actual wind speed to the mean eostrophic one is 81 to 88 per cent, except near the ground surface. It was impossible to find a certain value as an Austausch coefficient in a shallow layer on the land, though it was about 105 C. G. S. at many places. In Section 5, it was found that the lower atmosphere in the Rocky mountains region was a source of kinetic energy as well as of available potential energy, in so far as January 1957.
Distributions of heat gain or loss in a whole layer from the ground surface to 500mb level as well as at some specified levels are presented in Section 2. At most places a heat sink is seen near the ground surface while heat sources appear at some places in some upper layers. One of the factors of heat gain is the heat released by condensation of water vapour, and the region where large amount of condensation is estimated coincides well with the region of heat source. Cooling of an air column below 500mb level due to long wave radiation is estimated to be 300ly•day-1 or thereabout. Exchange of sensible heat between the ground surface and atmosphere is supposedly smaller than the heat gain or loss by the above two factors. Calculation of budget of water vapour shows that net condensation is in excess of observed amount of precipitation in some regions and in deficit in thers. At the former regions, weather condition such as cloudy without precipitation is observed frequently. It seems necessary to study role of cloud as a conveyance of moisture.