On the Temperature of Rain
1942 Volume 20 Issue 4 Pages 116-124
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1942 Volume 20 Issue 4 Pages 116-124
In this paper the author observed rain-water temperature for a year, and discussed some properties of rain-water temperature. The number of times which observed rain temperature is 218, and observed rain is 56 times. There are many kinds of rainfall types, but these kinds will be classified into four great divisions as following,
i) convectional type, ii) anti-cyclonic type, iii) cyclonic type, and iv) middle type.
In Fig. 2 the relation between τ (=t-T. t: air temperature and T: rain-water temperature) and t is shown, and frequency of τ for each types of rainfall is tabulated in percentage for total. It follows from these figures and table that the range of rain-water temperature increases proportionally to the air-temperature, and there was not an inversion of temperature when the rainfall types is convectional. But at cyclonic type rainfall the inversion of temperature was observed, and the rainfall will begin at this layer.
As shown in Fig. 4 the relation between fall of air temperature and fall of rain-water temperature, and between the former and the maximum τ are almost linear, while the variation of fall of τ with fall of air temperature is not systematical. The variation of fall of air temperature with rain duration is shown in Fig. 5 and the variation of fall of rain-water temperature is shown in Fig. 6. It appears from these figures that the maximum of fall of air and rain-water temperature occurs at five or six hours of rain duration.
The relation between fall and the maximum of τ of convectional rain and rain duration is shown in Fig. 7. The maximum value of τ is almost constant, and independent of rain duration. The most active centre of convectional rain appears after six or seven hours from benining of the rain.
It will be said from these facts that the convectional rain begins from the bottom or upper part of cumulo-nimbus, and the former rain phenomena gradually extends to the upper part of the clouds, and the later rain to the bottom part.
Next, the relations between amount of rainfall and fall of air and rain-water temperature of convectional rain are shown in Fig. 8, and the maximum τ and fall of τ are shown in Fig. 9.
