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Calibration of Leaf Resistance Porometers 1
Author(s) -
McCree K. J.,
Bavel C. H. M.
Publication year - 1977
Publication title -
agronomy journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.752
H-Index - 131
eISSN - 1435-0645
pISSN - 0002-1962
DOI - 10.2134/agronj1977.00021962006900040049x
Subject(s) - calibration , humidity , wetting , materials science , relative humidity , environmental science , water vapor , surface (topology) , composite material , meteorology , physics , mathematics , geometry , quantum mechanics
Leaf resistance porometers are normally calibrated by placing the humidity sensor over a wet surface, which is at a known temperature. A perforated plate of known diffusive resistance is placed between the surface and the sensor. The results are subject to systematic errors due to wetting of the calibration plate from below, condensation on the plate, and evaporative cooling of the wet surface. The possibilities for error were investigated, using commercially available equipment, and it was found that they could be greatly reduced by taking such simple precautions as placing a spacer between the wet surface and the plate, avoiding conditions in which the temperature of the plate might be less than that of the surface, and maintaining a humid atmosphere throughout the calibration.