A device or tool used to estimate relative humidity and other psychrometric properties of air based on the temperature difference between a standard thermometer and a thermometer with a wet wick exposed to airflow. The temperature difference observed between the two thermometers is then used, often with the aid of a psychrometric chart or calculation, to determine humidity levels, dew point, and other air properties. These calculations provide valuable insights into air moisture content.
This determination is critical in several fields, ranging from meteorology and HVAC (Heating, Ventilation, and Air Conditioning) to agriculture and industrial processes. Knowing the humidity levels assists in weather forecasting, ensures efficient climate control in buildings, aids in preserving crops, and optimizes specific manufacturing operations. Historically, such measurements relied on manual charts and careful observation; contemporary versions often incorporate digital sensors and automated calculations, enhancing accuracy and usability.