On the Transmissibility of Light through a Cloud Particles(For the Wave-Lengths from 4320 Å to 9500 Å.)

[摘要] The measurements of the transmission of light through the following three different kinds of artificial fog and smoke were made in the visible range of 4300 Å to 7500 Å and in the infra-red range of 7500 Å to 9500 Å. The same apparatus as in the previous experiments was used. The measurements were done by using a glass-spectrograph and a wooden cloud chamber which is 400cm long, 30cm wide. and 30cm high, The three kinds of the fog and smoke are:(1) Fog condensed from the aqueous vapour of low pressure was introduced into the cloud chamber.(2) Fog was made directly from water by using a sprayer.(3) Smoke of tobacco was introduced into the chamber.As to the artificial fog produced from the aqueous vapour of low pressure, a maximum of transmission coefficient was found at about 4700 Å and a minimum around 5050 Å. As the wave-length increased, the transmission coefficient also seemed to increase, but some decrease was found at 8100 Å to 9500 Å.As to the fog produced with a sprayer, a maximum was also found at 4700 Å and its value decreased gradually as the wave-length increased. A small increase was found at 7500 Å to 8100 Å, but a gradual decrease was again noticed at 8100 Å to 9500 Å.As to the smoke, a maximum of transmission coefficient was found at about 4800 Å and a minimum at about 5200 Å. From this minimum point, the coefficient increased gradually as the wave-length increased through 6500, 7500, 8100, to 9500 Å.The sizes of the fog and smoke particles used in this experiment were measured, except that of the aqueous vapour.From the results obtained by the previous experiments, it was found that Rayleigh's formula of scattering is not satisfied, and it might be pointed out that King's formula is not applicable to the scattering of light by water particles produced with sprayers.

[学科分类] 大气科学