On the New Atmometer for Ecological Research Use (The First Report)

[摘要] Various types of atmometers have been devised and described from time to time, but the types of atmometers which have been used generally throughout the ecological world in Japan are spherical porous-poreclain atmometer by Livingston and filter paper atmometer by Hirata. In this paper are reported the new atmometer which improved upon two atmometers.I Mounting and use of the new atmometer.The new atmometer consists from following two parts. grass reservior and cylindrical filter paper for Soxhle-extractor use (see Fig. 1 & 2) The cylindrical filter paper is 35mm in outside diameter and 150mm high, the top closed and rounded, the bottom open and submerged into the water of reservior, and the glass reservior is 70mm in outside diameter and 26mm high.The length of cylindrical filter papre and the diameter of glass reservior should be taken suitable ones according to evaporating power and purpose of measurement.Evaporation occurs from the outer surface of the cylindrical filter paper and water moves with evaporating up from the reservior below. Readings are secured from time to time by weighing the amount of water lost from the reservior during the observeation period. In this instrument is to be used only distilled water and some formaldehyde added to the water used for storage hinders the development of fungi.II Simple experiments for the new atmometer.As the results of simple experiments to the difference of eveaporating faculty from individual instrument or level of water in the reservior orusing or inclining of the instrument have been knowm that the new atmometer is excellent to measure evaporating power in the air (see table 1, 2, 3 & 4).III Comparison with the new atmometer and other atmometer by same principle.Chief excellent properties of the new atmometer are as follows.(1) The new atmometer is cheap in fabrication and the handling and use are simplest.(2) Evaporating faculties of each atmometers are possible to keep uniform under the constant condition by renewing the cylindrical filter paper.Therefore it is unnecessary that as such Livingston's atmometer. etc. every reading from atmometer in use is to be multiplied by the correction coefficient and frequent restandardization of the atmometer is desirable.(3) This atmometer is far more sensitive to small differences in micro-climate by changing the size of reservior and cylindrical filter paper than is any other atmometer for ecological research use.As defects of this atmometer it may be taken in consideration at first that measurement of the amount of true evaporation in rainfall time is impossible as like other any evaporimeters and moisture content in the upper and lower parts of the cylindrical filter paper differs. but the later defect is often significant when the atmometer was compared with plant physiology. The result of measurement of evaporation when it is rained during the observation period. has been corrected by otherwise mounted atmometer of which is not reached cylindrical filter paper to bottom of glass reservior, to measure the amount of rain water penetrating in to the reservior.

[学科分类] 大气科学