Abstract
Using a photomultiplier tube and filters, the intensities of ultraviolet sky radiation from various directions were measured at Mt. Norikura in summer 1957. The measurement was done in two different wave-length ranges, i. e.3200Å and 3300Å or so respectively, with the aim of finding the effect of the ozone layer in the upper atmosphere. The measurement of the intensities of U. V. sky radiation was done in three directions in the principal meridian plane, that is, in the zenith distance of 15°towards the sun, just in the zenith and in that of 15° backward of the sun. Also each measurement was carried out at every four or five minutes during the time when the sun's altitude was from 0° to 30°. The relative values were computed at each instant taking the values in the zenith as a unit. Then their time variation was examined especially in view of its difference between the two wave lengths. Investigating the results of observation a rapid increase of the difference was pointed out when the sun's altitude was lower than two or three degrees.
These phenomena were theoretically analyzed, computing the primary scattered intensities in the atmosphere with a typical absorption layer and also without it. And the above-mentioned feature was proved to be the effect of an ozone absorption layer. Thus a new method of determining the vertical distribution of the atmospheric ozone was suggested.
