Abstract
Dissolved oxygen content in rainwater has been measured in Tokyo by means of the Winklar's titration method since September 1957. The sample of rainwater has been collected in a bottle containing a liquid paraffin. In most rainfalls rainwater was found to be unsaturated with the dissolved oxygen at the time of its arrival to the ground as Miyake and Saruhashi (1949) pointed out, its saturation percentages being between 85 and 100% for rainfalls during the period of September 1957 to March 1958. Snow was found to contain about 6cc oxygen per litre of melted snow, which is about 60% as compared with the oxygen content of saturated water at 0°C and normal pressure.
Values of oxygen content for each precipitation were related to the structure of raincloud. This shows that the oxygen content in rainwater has a close correlation with the height of cloud base and with the mechanism of raindrop formation. A possible explanation for the cause of the unsaturation and the significance of the obtained results for studies of precipitation mechanism are discussed.
