Mediciones climáticas de humedad del aire en los trópicos, con termistores y la ecuación sicrométrica

Abstract

Electronic devices for air humidity measurements with hygroscopic capacitance sensors were tested for periods longer than a year under tropical conditions in Costa Rica. Some of the, showed a calibration drift that produced errors as high as 20% relative humidity after several months of use. To present a low-cost alternative for electronic air humidity measurements in the tropics, two thermistors were used as wet-dry bilb thermometers. Simultaneous measurements with an Assmann aspiro-psychrometer and the thermistors showed that five-minute average temperatures were within 0.2°C and relative humidities within 2%. Copper-constantan thermocouples yielded similar results. It was proved that thermistors are appropriate to be used year after year, as needed in climatological stations,, without replacement or recalibration.