U.S. Department of Agriculture: Agricultural Research Service, Lincoln, Nebraska


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Published in Micrometeorology in Agricultural Systems (2005) Agronomy Monograph no. 47: 31-41


Humidity is, together with temperature and pressure, one of the fundamental variables that characterize the local state of the atmosphere. Within the realm of agriculture, humidity measurements have a wide variety of applications, including prediction of plant diseases, prediction and maintenance of livestock comfort levels, estimation of evapotranspiration, and planning of hay and grain harvests. In micrometeorology, measurements of temporal and spatial gradients in humidity are used to infer fluxes of water vapor between surface and atmosphere. The requirements for these various applications can be quite different, so the choice of an appropriate measurement method or instrument necessitates some understanding of the underlying principles.