Observation of the Distribution of Ultraviolet Sky Radiation at Comparatively Low Altitude of the Sun

[摘要] Observation of the angular distribution of ultraviolet sky radiation in the principal meridian plane were made at the summit of Mt. Fuji and at Tokyo by means of a photoelectric cell and filters mounted on a theodolite when it was almost at the sunset and also when the sun's altitude was 30°.Regarding the observed relative intensities at various zenith distances, relatively high values at larger zenith angle were pointed out either when the wave-length of measured radiation was the shorter one or when the elevation of observing place was the higher one. These were both attributed to the effect of decreasing optical thickness of the scattering atmosphere which had already been discussed by the present author.An investigation on the effect of the ozone layer was done by observing the intensity ratio of the two different ranges of U. V. sky radiation at the zenith. The well-known “Umkehr Effect” was observed, thus showing a possibility of observing the ozone layer by means of this sort of apparatus.

[学科分类] 大气科学