Cosmic-Ray Intensities and Fronts

Cosmic Ra_??_s as a Possible Meteorological Factor, III

Abstract

This memoir is essentially a sequel to one which we recently published in this journal with the title “Cosmic-Ray Intensities and Air Masses”. The determination of the influence of cold and warm fronts on cosmic-ray intensities, using the materials during the period 1937-1939, constitutes the main subject of discussions in the present paper.
The cosmic-ray intensity (after reduction to the normal pressure) is almost constant in general, within the accuracy of observation at least, on the passage of individual cold fronts (the intensity increases 0.12% in mean on 8 representative cold-front passages), but it decidedly decreases on the passage of marked warm fronts. Fig. 2 illustrates a remarkable warm front from which heavy rainfalls resulted over Kwantô District during the period, June 28-July 5, 1938⁽¹⁾. It is well known that in our latitudes a warm southerly current of great depth accompanied with the passage of warm front might extend upwards to a height of 10 or 15km without losing its intensity, while a cold northerly current is shallow and seldom exceeds some 3km of height. It is therefore obvious from these data that the depth of cold or warm air would bring pronounced varieties in the cosmicray intensities.
The distribution of cosmic-ray intensities in the area of migratory thunder is shown in Fig. 3, which illustrates the structure of thunder of cold-front type.