Ultrasonic detection of atmospheric humidity variations
- 27 February 2001
- journal article
- Published by AIP Publishing in Review of Scientific Instruments
- Vol. 72 (3) , 1910-1913
- https://doi.org/10.1063/1.1347973
Abstract
The small variation of the speed of sound in air with water vapor concentration is evaluated as a method of measuring atmospheric humidity. Laboratory acoustic phase measurements were made, using inexpensive piezoelectric transducers and electret microphones with dew point temperature independently monitored in the same enclosure. Phase variations from an acoustic path gave fair agreement with the measured humidity variations, when temperature and cross-wind variations were removed. Thermal stabilization and filtering were necessary to reduce the random phase noise contributions from the detectors, leading to errors in mean vapor pressure of ∼5 mbar at 20 °C. The approach is therefore more suited to determine turbulent humidity fluctuations, for meteorological latent heat flux measurements.Keywords
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