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A low‐cost psychrometer for field measurements of atmospheric humidity
Author(s) -
ALLEN S. J.,
BRENNER A. J.,
GRACE J.
Publication year - 1994
Publication title -
plant, cell and environment
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.646
H-Index - 200
eISSN - 1365-3040
pISSN - 0140-7791
DOI - 10.1111/j.1365-3040.1994.tb00286.x
Subject(s) - hygrometer , wet bulb temperature , humidity , environmental science , saturation (graph theory) , meteorology , remote sensing , atmospheric sciences , mathematics , geology , geography , combinatorics
A design for an aspirated wet and dry bulb psychrometer, suitable for continuous field measurement of atmospheric humidity, is described. The psychrometer is simple and cheap to make, with a material cost of UK £40 per unit. It is mainly constructed from ready‐made plastic plumbing parts, thus avoiding the need for expensive workshop facilities. The wet and dry bulb temperature sensors are suitable for direct connection to a solid‐state data‐logger. During extensive field use, it has proved reliable and easy to maintain. The accuracy of the device was assessed by intercomparison with an Assman psychrometer, a standard instrument for measuring atmospheric humidity. The test was conducted under high ambient saturation deficits (4.08 ± 1.22 kPa) and shortwave radiation fluxes in Niger, West Africa. Reasonable agreement between the two instruments was observed, with the low‐cost psychrometer giving a mean saturation deficit 0.12 ± 0.25 kPa higher than the Assman.