Effects of Relative Humidity on Temperature Dynamics in Natural Ecosystems: Comparison of Measured and Model-Predicted Data

Understanding the factors influencing temperature variations in natural ecosystems is crucial for processes such as species distribution, phenology, and carbon cycling. This article presents a theoretical framework that investigates the impact of relative humidity (RH) on these variations. Previous analyses based solely on environmental thermodynamics governed by radiation and the Stefan–Boltzmann law, named the dry model, revealed a nocturnal cooling rate of approximately 0.9 °C/h in low-relative-humidity conditions (<85%) using data of three distinct Brazilian forests within the Amazonian biome. However, this rate decreased significantly at higher RH, suggesting an additional heating effect, which is likely attributed to the coalescence of water molecules in the air. In this study, a novel humid model is developed, integrating terms proportional to RH and its time derivative. This model is based on the premise that clusters of water molecules and latent heat depend on the quantity of water molecules and intermolecular forces. The findings demonstrate a superior fit to the data using the proposed model, with R2 values ranging from 0.7 to 0.95, effectively capturing both the nocturnal temperature decline and diurnal variations. This advancement is significant as it underscores the importance of considering water molecule clusters in developing a more precise model that improves upon the dry model methodology.