On the Annual and Diurnal Variation of the Amount of Solar Radiation at Several Places in Japan

[摘要] In this second report on the study of observations of direct solar radiation made by means of silver-disk pyrheliometers, the author discussed annual and diurnal change of solar radiation as well as the variation of atmospheric turbidity at eleven meteorological stations during the interval between August 1932 and July 1933. The principal results of the present investigations are as follows:i) The coefficients of turbidity (Feussner u. Dubois, 1930) calculated from monthly mean values of solar radiation show that the values, in general, were in minima at about December, and then began to increase until May, when the values were generally at their maxima. This seems to be in agreement with the results obtained at several European and American observatories.ii) It is interesting to note that there is the tendency to give greater values of coefficient of turbidity observed at 12h than that of 9h, or 15h. The tendency above noted seems to be in connection with the formation of invisible condensation products of water vapour in the daily ascending air current and increase of dust in the lower part of air.iii) Assuming the coefficient of turbidity actually calculated from observations, the diurnal variation of the intensity of solar radiation were calculated for four seasons at five selccted stations respectively, and then by means of graphical integration, calculated total amount of solar radiation were determined.

[学科分类] 大气科学