Abstract
The comparative observations of the black and the white thermometer s_??_reens provided with the dry-bulb and the wet-bulb thermometers in them were made at the Central Meteorological Observatory, Tokyo during one year from Dec. 1942 to Nov. 1943.
The same comparative observations were also made from Jan. 22nd to Feb. 25th, 1942 with the other thermometers and another white thermometer screen of the same type.
The results are summarized as follows:
(a) Air temperature. The remarkable difference occurs a ab ut 14h. The maximum difference is +1.2°C and in fine weather it is controlled by several elements except solar radiation.
(b) Wet-bulb temperature. Compared with the case of air temperature, the difference is generally small, showing almost the same results at night.
(c) Water vapour tension. When air temperature is above 25°C, the difference ranges from +4.5 to -1.8mm Hg_??_ Its ratio, however, is almost the same both in summer and winter, the fluctuation being 4% or so, while, when air temperature is below 25°C, the difference is trivial in spring and at night.
(d) Relative humidity. The mean difference is the smallest of the present results throughout the year, showing the fluctuation of 2% or so. No marked diurnal variation is found.
