The present paper is the result of the observations of the water of the Ohori (castle-moat) in the spring-time of 1933 and some experimental investigation which was carried out in aquaria, using Synedra salina cultured in it as material of phgtoplankton. 1. As far as the results obtained by the study of the water of the Ohori are concerned, the diatom increase in the spring-time is fairly accelarated by the rise of water-temperature and by the increase of solar radiation, provided the necessary nutrient salts are available. 2. Even if other conditions be suitable, when the water-temperature is above 14°C. the multiplication of Synedra salina is greatly checked. 3. Synedra sinks down into the bottom layer to avoid the too strong solar radiation when the weather is fine and vice versa. 4. The average amount of salts consumed by Sunedra salina of 10, 000per c. c. in the layer of 15cm to 25cm. in depth are 1.45mg/L. in SiO2, 0.006mg. in P2O5 and 0.017mg. in N2O5-N, when the solar radiation is calculated 1, 000gr. cal./cm2., while in the surface layer no consumption of nutrient salts oceurred, as there was too strong solar radiation and so there no multiplication of Sunedra occurred. 5. In the place where there was no direct sunlight the consumption of nutrient salts by Synedra did not occur at all.
Recently, C.-G. Rossby has studied the generalizaion of the theory. of the mixing length from a dynamical symirality of the two dimentional air motion that one of his obtained results the coeffcient of eddy viscosity is propotional to the square of the distance. In this paper, we used his results and calculated the vertical change of the horizontal air currents and the circular distribution of the horizontal winds. Again we obtained the same results like as the former our paper that the relation between the surface winds and gradient winds. Also we showed the mechanism of the vertical, change of the upper air of the tropical depression and phenomena of the eye of typhoon.
It is a well-known fact that during the cold season the diurnal change in the velocity of westerly winds is often experienced especially in Kwanto distrlct afer the passage of a developing cyclone to the east of Japan proper. As a result of investigation, the cause of this phenomena was found to due to the striking contrast in the amplitude of daily temperature waves in Kwanto plain and the central plateu district. In the daytime, owing to the excessive rise of the air temperature in Kwanto district, the cold and heavy air flows sweeping over our district as descening current being unable to keep the stable equilibrium, but at night the case is opposite. Combining this periodic flow of air with the steady gradient winds which come from the west, then the resultant winds develop strongly in the daytime while they fall calm in night-time.
The frequency (denoted by Nn) of the case that dayly mean air-temperature had lasted n days to rise was found statistically to be represented well by the formula, here A and α being constants to be determined from the data of observation. As to the case of falling of the temperature, the same formula was obtained. The author used the data of the observations at Kyôto and at Yagi.