High Relative Humidity Levels Research Articles

Beyond static: Tracking the dynamic nature of water absorption and Young's modulus in IPMC devices

AbstractIonomeric polymer‐metal composites (IPMC) are advanced materials designed to mimic biological systems. Their performance depends on various factors, including electrical stimulus intensity, membrane hydration, ionic migration, and Young's modulus. However, there is a lack of studies in the literature investigating how the water absorption capacity and elastic modulus change over time in IPMCs. Understanding the hydration level variation as a function of time is essential because as this parameter deviates, the ionic migration capacity and Young's modulus also change, altering the device's electromechanical efficiency over time. To address this research gap, Nafion/Pt‐based IPMC devices exchanged with four monovalent cations (H+, Li+, Na+, and K+) and one ionic liquid (1‐butyl‐3‐methylimidazolium—BMIM+) were prepared, and a comprehensive investigation on how the water absorption capacity and Young's modulus vary as a function of time, relative humidity (RH), and counterion size was performed. The results revealed that the water uptake capacity is significantly higher and occurs more rapidly at higher RH levels and when the counterion's ionic radius decreases. Consequently, the time required for the device to reach osmotic equilibrium can range from 40 to 270 min, depending on the RH and counterion used. Furthermore, it was observed that the first natural frequency and Young's modulus also exhibit time‐dependent behavior. Under constant RH conditions, the mechanical properties of the IPMC can vary by up to 50% in less than 60 min. Notably, the combined results from water uptake capacity, Young's modulus, electrochemical impedance spectroscopy, and electromechanical response analyses (including blocking force, displacement, displacement rate, current, coulombic efficiency, and voltage) suggest that a morphological transformation within the polymer is likely to occur once RH exceeds 60%. This finding strengthens the hypothesis that ion migration is mainly influenced by their movement through Nafion's ionomeric channels rather than the filling of ionic agglomerates.

Evaluating the effects of heatwave events on hydrological processes in the contiguous United States (2003–2022)

Extreme heat and drought conditions are affecting water availability in many regions worldwide, leading to negative impacts on human societies, agriculture, and ecosystems. However, current research lacks comprehensive spatiotemporal analysis examining the interplay between multiple hydrological factors and heatwave events, especially in the context of climate change. This research broadly pertains to understanding the dynamics of hydrological factors and their potential responses to heatwave during warm seasons across the contiguous United States for the period from 2003 to 2022. Utilizing data from the Global Land Data Assimilation System (GLDAS), we analyzed surface runoff, evapotranspiration (ET), precipitation, Groundwater Storage (GWS), Root Zone Soil Moisture (RZSM), and Total Water Storage (TWS) to discern annual patterns and the impacts of heatwave. The spatial patterns of heatwave highlighted a higher occurrence in the western, central, and northeastern U.S., with longer average durations in the western and south-central regions. These events are predominantly dry, characterized by low Relative Humidity (RH), except in the southeastern U.S., where heatwave coincide with high RH levels. Post-heatwave analysis indicated a reduction in GWS, TWS, RZSM, and ET, alongside an increase in surface runoff, RH, and precipitation. An in-depth examination of rainfall and temperature dynamics during heatwave revealed weak correlations between rainfall and temperature, as well as between rainfall and heatwave duration, highlighting the complex nature of these interactions. The study also found an enhanced probability of rainfall following heatwave, particularly in the eastern regions, drawing attention to the potential for increased flood risks post-heatwave. Our findings contribute to the growing body of knowledge on the impacts of heatwave on hydrological factors, providing valuable insights for climate change adaptation and water resource management strategies.

Effects of Gas-Diffusion Layers and Water Management on the Carbon Corrosion of a Catalyst Layer in Proton-Exchange Membrane Fuel Cells

Carbon corrosion in a catalyst layer (CL) deteriorates the performance and durability of proton-exchange membrane fuel cells (PEMFCs), which are closely related to water management within these cells. This study investigates the characteristics of water behavior of two gas diffusion layers (GDLs) and compares their influence on degrees of degradation in the CL. First, the properties of the GDLs, including their thickness, pore size distribution, gas permeability, electrical resistance, contact angle, and polytetrafluoroethylene (PTFE) content, are evaluated. The dynamic behavior of liquid water is observed using a visualization cell and synchrotron X-ray imaging. Second, a modified accelerated stress test (AST), which includes a water generation reaction within the catalyst support protocol of the US Department of Energy (DOE), is performed. For assessing the degradation, we utilize polarization curves, electrochemical impedance spectroscopy, cyclic voltammetry, scanning electron microscopy, and field emission transmission electron microscopy. The results reveal that, even though GDL B contains a higher hydrophobic content than GDL A, it exhibits lower water discharge, indicating a reduced performance at high relative humidity (RH) levels. This is attributed to a low capillary pressure gradient, which is influenced not only by PTFE but also by the overall pore structure (i.e., porosity and pore size). Consequently, a high capillary pressure gradient can enhance water discharge and thereby mitigate carbon corrosion and Pt agglomeration in the CL. In addition, the application of the modified AST induces carbon corrosion with fewer cycles than that achieved using the DOE carbon support protocol.

The impact of short-term exposure to meteorological factors on the risk of death from hypertension and its major complications: a time series analysis based on Hefei, China.

This study aimed to reveal the short-term impact of meteorological factors on the mortality risk in hypertensive patients, providing a scientific foundation for formulating pertinent prevention and control policies. In this research, meteorological factor data and daily death data of hypertensive patients in Hefei City from 2015 to 2018 were integrated. Time series analysis was performed using distributed lag nonlinear model (DLNM) and generalized additive model (GAM). Furthermore, we conducted stratified analysis based on gender and age. Relative risk (RR) combined with 95% confidence interval (95% CI) was used to represent the mortality risk of single day and cumulative day in hypertensive patients. Single-day lag results indicated that high daily mean temperature (T mean) (75th percentile, 24.9°C) and low diurnal temperature range (DTR) (25th percentile, 4.20°C) levels were identified as risk factors for death in hypertensive patients (maximum effective RR values were 1.144 and 1.122, respectively). Extremely high levels of relative humidity (RH) (95th percentile, 94.29%) reduced the risk of death (RR value was 0.893). The stratified results showed that the elderly and female populations are more susceptible to low DTR levels, whereas extremely high levels of RH have a more significant protective effect on both populations. Overall, we found that exposure to low DTR and high T mean environments increases the risk of death for hypertensive patients, while exposure to extremely high RH environments significantly reduces the risk of death for hypertensive patients. These findings contribute valuable insights for shaping targeted prevention and control strategies.

Robust Modeling for Factors Affecting in Relative Humidity in Basra Governorate

Basra Governorate is considered among the Iraqi governorates, with high levels of relative humidity sometimes, which makes the weather uncomfortable during the year. It was necessary to building in this research a robust regression model to study the effect of some factors such as the maximum and minimum temperatures, the amount of rainfall, atmospheric pressure, and the average amount of dust falling. When building linear regression models, many problems occur in which failure some of the hypotheses model. In this research, least squares estimates were compared with robust and found the preference for the method of S.

Development of smart control system for leakage warning in compact roofs

Smart Sensor technologies to monitor temperature and moisture conditions in building components, can be used to give automatic warnings for abnormal high levels of moisture. Flat compact roofs are of particular interest, especially due to their vulnerability to rain leakages through the roofing membrane. Installing moisture sensors in such a roof measuring relative humidity (RH) or free water may give an early warning of rain leakages or condensation due to air leakages from indoors – before they start to get problematic. One challenge is, however, that normal moisture redistribution in the insulation layer over the season or day may give very high levels of RH in the top or bottom part of the insulation. The sensor system must be able to distinguish between these normal levels and leakage events. Together with a sensor technology and control system producer we have previously developed a semi-quantitative system that defines typical or normal RH levels in the insulation layer during the year. This system was based on hygrothermal simulations for various conditions, such as different exterior climate and levels of built-in moisture. This paper presents the preliminary findings from the further development of the system using real measurements from two pilot buildings located in Norway.

Geometric Analysis of Free and Accessible Volume in Atmospheric Nanoparticles.

Computer-generated atomistic microstructures of atmospheric nanoparticles are geometrically analyzed using Delaunay tessellation followed by Monte Carlo integration to compute their free and accessible volume. The nanoparticles studied consist of cis-pinonic acid (a biogenic organic aerosol component), inorganic ions (sulfate and ammonium), and water. Results are presented for the free or unoccupied volume in different domains of the nanoparticles and its dependence on relative humidity and organic content. We also compute the accessible volume to small penetrants such as water molecules. Most of the free volume or volume accessible to a penetrant as large as a water molecule is located in the domains occupied by organics. In contrast, regions dominated by inorganics do not have any cavities with sizes larger than 1 Å. Solid inorganic domains inside the particle are practically impermeable to any small molecule, thereby offering practically infinite resistance to diffusion. A guest molecule can find diffusive channels to wander around within the nanoparticle only through the aqueous and organic-rich domains. The largest pores are observed in nanoparticles with high levels of organic mass and low relative humidity. At high relative humidity, the presence of more water molecules reduces the empty space in the inner domains of the nanoparticle, since areas rich in organic molecules (which are the only ones where appreciable pores are found) are pushed to the outer area of the particle. This, however, should not be expected to affect the diffusive process as transport through the aqueous phase inside the particle will be, by default, fast due to its fluid-like nature.

Worldwide potential of emissive materials based radiative cooling technologies to mitigate urban overheating

Radiative cooling has gained significant attention in recent years for its passive heat evacuation capabilities. Numerous materials have been developed, but comparing their cooling effectiveness has proven challenging due to inconsistent experimental conditions. This study aims to bridge this gap by evaluating the heat evacuation potential of various radiative cooling materials under consistent climatic conditions.Using a validated heat transfer model, the performance of eleven materials was simulated in twenty-two Urban Overheating-affected cities. The assessment considered factors such as radiated heat losses, solar heat gains, and convective heat losses to gauge the cooling power of each material. The simulation assumed an active system where the materials were placed on a highly conductive, uninsulated surface, akin to having a fluid at a constant temperature beneath.The ability of materials to radiate heat and cool down depends on their optical properties. The findings suggest limited benefits in equatorial climates, with an average monthly total heat exchanged (MATHE) of −19.73 kWhm−2. Materials displayed consistent behavior throughout the year in climates with high relative humidity levels. Climates with elevated ambient temperatures derived the greatest advantages from strictly selective and highly reflective materials that emitted within the atmospheric window. Arid climates showed potential during transition times (MATHE -74.5 kWhm−2), while warm temperate climes benefited during summer months (MATHE -112.1 kWhm−2). In snow zone climates, the system could be utilized year-round for cooling-intensive scenarios, with a MATHE of −203.8 kWhm−2. This study evaluates radiative cooling materials' effectiveness in different climates, informing energy-efficient cooling applications.

Assessment of the Correction of the Reference Evapotranspiration at Nonirrigated Weather Stations Affected by Aridity and Delimitation of the Meteorological Conditions that Limit its Implementation

As most reference crop evapotranspiration (ETref) estimates are computed from weather stations located outside irrigated plots, the site aridity can produce ETref overestimation. To obtain more reliable ETref estimates, the potential of using the methodology that corrects the observed air and dew point temperatures was first analyzed in this study, and the meteorological conditions that limit this methodology implementation were subsequently assessed. A statistical analysis was conducted of pairwise comparisons between a station under reference conditions (Montañana) and four nearby stations affected by aridity in Spain for 2020. The daily reference evapotranspiration was calculated with the FAO56 Penman–Monteith equation (ETo PM), and afterward, the corrected daily reference evapotranspiration (ETo PMcor) was obtained using the previously mentioned correction methodology. The statistical analysis showed a greater connection between ETref and ETo PMcor in all pairwise comparisons, with the strongest connection reached between ETref Montañana station and ETo PMcor Pastríz station (coefficient of determination r2 = 0.98 and root mean square error RMSE = 0.34 mm/day.). This ETo PM correction methodology was established considering a difference between the minimum temperature (Tmin) and the dew point temperature (Tdew) greater than 2 °C, as this value is considered the benchmark of aridity, but this research found that high aridity (P/ETo < 0.5) inland locations and high aridity coastal locations with high relative humidity (RH), markedly as of 61.5% and 68%, respectively, could exhibit days where Tmin-Tdew < 2 °C does not reflect well-watered soil and healthy grass but rather high RH levels (r2 = 0.77 and 0.57, respectively). As this correction methodology was not established considering Tmin-Tdew values smaller than 2 °C, the application scope of this methodology is limited under the above scenarios.

Numerical-experimental approach to identify the effect of relative humidity on the material parameters of a rate-dependent damage model for polyamide 66

This work aims at identifying the behavior of polyamide 66 (PA66) under different Relative Humidity (RH) conditions using a phenomenological model that accounts for viscoelastic and viscoplastic rheology coupled to ductile damage. An experimental approach is designed considering different loading conditions, namely: monotonic at several strain rates, loading–unloading, creep-recovery, and cyclic tests. These experiments are chosen to discriminate the various active mechanisms governing the nonlinear behavior of PA66. The thermodynamic background of the phenomenological model, the evolution laws, and the accompanying RH-dependent material parameters are presented and discussed. Using the experimental findings, an optimization algorithm is adopted to identify the model parameters. The latter are investigated with regard to the relative humidity, leading hence to the development of a model that accounts for the effect of RH on all inelastic mechanisms and ductile damage. Validation through experimental data for RH = 0%, 25%, 50%, 65%, and 80% reveals that the current model captures the effect of RH and yields mechanical responses in good agreement with experimental findings, notably at higher RH levels. The current numerical-experimental framework presents a unified model for a wide range of humidity conditions and provides a better insight into material properties and rate-dependent inelastic mechanisms under humidity exposure, which typical models do not provide. In addition, the present constitutive law is easily adoptable in micromechanics schemes for the study of polymer based composite materials and structures.

Zero Threshold for Water Adsorption on MAPbBr3

Hybrid organic-inorganic perovskites (HOIPs) have shown great promise in a wide range of optoelectronic applications. However, this performance is inhibited by the sensitivity of HOIPs to various environmental factors, particularly high levels of relative humidity. This study uses X-ray photoelectron spectroscopy (XPS)to determine that there is essentially no threshold to water adsorption on the in situ cleaved MAPbBr3 (001) single crystal surface. Using scanning tunneling microscopy (STM), it shows that the initial surface restructuring upon exposure to water vapor occurs in isolated regions, which grow in area with increasing exposure, providing insight into the initial degradation mechanism of HOIPs. The electronic structure evolution of the surface wasalso monitored via ultraviolet photoemission spectroscopy (UPS), evidencing an increased bandgap state density following water vapor exposure, which is attributed to surface defect formation due to lattice swelling. This study will help to inform the surface engineering and designs of future perovskite-based optoelectronic devices.

An Efficient Ambient-Moisture-Driven Wearable Electrical Power Generator.

Existing devices for generating electrical power from water vapor in ambient air require high levels of relative humidity (RH), cannot operate for prolonged periods, and provide insufficient output for most practical applications. Here a heterogeneous moisture-driven electrical power generator (MODEG) is developed in the form of a free-standing bilayer of polyelectrolyte films, one consisting of a hygroscopic matrix of graphene oxide(GO)/polyaniline(PANI) [(GO)PANI] and the other consisting of poly(diallyldimethylammonium chloride)(PDDA)-modified fluorinated Nafion (F-Nafion (PDDA)). One MODEG unit (1 cm2 ) can deliver a stable open-circuit output of 0.9V at 8µA for more than 10h with a matching external load. The device works over a wide range of temperature (-20 to +50 °C) and relative humidity (30% to 95% RH). It is shown that series and parallel combinations of MODEG units can directly supply sufficient power to drive commercial electronic devices such as light bulbs, supercapacitors, circuit boards, and screen displays. The (GO)PANI:F-Nafion (PDDA) hybrid film is embedded in a mask to harvest the energy from exhaled water vapor in human breath under real-life conditions. The device could consistently generate 450-600mV during usual breathing, and provides sufficient power to drive medical devices, wearables, and emergency communication.

MOF-801/Graphene Adsorbent Material for Greenhouse Climate Control System—Numerical Investigation

Greenhouses with efficient controlled environment offer a promising solution for food security against the impacts of increasing global temperatures and growing water scarcity. However, current technologies used to achieve this controlled environment consume a significant amount of energy, which impacts on operational costs and CO2 emissions. Using advanced metal organic framework materials (MOFs) with superior water adsorption characteristics, this work investigates the development of a new technology for a greenhouse-controlled environment. The system consists of MOF coated heat exchanger, air to air heat exchanger, and evaporative cooler. A three-dimensional computational fluid dynamics (CFD) model was developed using COMSOL software and experimentally validated for the MOF-801/Graphene coated heat exchanger (DCHE) to determine the best cycle time and power input. It was found that using desorption time of 16 min and power input of 1.26 W, the maximum water removal rate was obtained from MOF-801/Graphene of 274.4 g/kgMOF/W.hr. In addition, an overall mathematical model for the greenhouse climate control was developed and used to investigate the effects of air humidity and velocity on the input air conditions to the greenhouse. Results showed that with high relative humidity levels of 90% in the greenhouse can be conditioned to reach the required relative humidity of 50%.

Properties of Autoclaved Aerated Concrete in Different Curing Conditions: A Review

Abstract: Autoclaved aerated concrete (AAC) has many benefits for structures, such as heat insulation, sound insulation, fire resistance, reduced dead weight, and many more. AAC products include blocks, wall panels, floor and roof panels, and lintels. Besides its insulating capability, one of AAC's advantage in construction is its quick and easy installation since the material can be routed, sanded, and cut to size on-site using standard carbon steel band saws, hand saws, and drills. Although AAC has been produced for many years, there are still some points that need to be clarified. One of these points is the effect of humidity intrusion on AAC members in areas with high relative humidity levels, like Mediterranean climates. Therefore, various tests associated with the mechanical and physical properties of AAC concrete should be carried out, particularly Compressive Strength test in order to assess the strength of AAC blocks. The current project intends to analyse the physical and mechanical properties of autoclaved aerated concrete blocks at three different curing conditions using an accelerated curing tank to compare the effects of curing on the properties of AAC

Acoustic activity of bats at power lines correlates with relative humidity: a potential role for corona discharges.

With the ever-increasing dependency on electric power, electrical grid networks are expanding worldwide. Bats exhibit a wide diversity of foraging and flight behaviours, and their sensitivity to anthropogenic stressors suggests this group is very likely to be affected by power lines in a myriad of ways. Yet the effects of power lines on bats remains unknown. Here we assessed the responses of insectivorous bats to very high voltage power lines (VHVPL; greater than 220 kV). We implemented a paired sampling design and monitored bats acoustically at 25 pairs, one pair consisting of one forest edge near to VHVPL matched with one control forest edge. Relative humidity mediates the effects of power lines on bats: we detected bat attraction to VHVPL at high relative humidity levels and avoidance of VHVPL by bats at low relative humidity levels. We argue that the former could be explained by insect attraction to the light emitted by VHVPL owing to corona discharges while the latter may be owing to the physical presence of pylons/cables at foraging height and/or because of electromagnetic fields. Our work highlights the response of bats to power lines at foraging habitats, providing new insight into the interactions between power lines and biodiversity.

Full‐field hygroscopic characterization of tough 3D‐printed supramolecular hydrogels

AbstractChain‐extended ureido‐pyrimidinone poly(ethylene glycol) (CE‐UPy‐PEG) is a supramolecular hydrogel with excellent mechanical properties and shape memory capabilities, making it highly suitable for 3D printing of complex biomimetic structures to mimic biomaterials. However, its transient hygroexpansion response under environmental change, specifically relative humidity (RH), which is strongly affected by the supramolecular sub‐structure, is poorly understood. Therefore, a high‐precision full‐field fiber‐swelling methodology is applied to 3D‐printed CE‐UPy‐PEG fibers, enabling investigation of the influence of PEG chain length (1.5, 3, and 10 kg/mol studied here) and RH rate from wet to dry on the longitudinal and transverse surface strain evolution during multiple RH cycles. The PEG length directly influences the fibers' hygroscopic properties, because only CE‐UPy‐PEG3k and CE‐UPy‐PEG10k exhibit a phase transformation from semicrystalline to amorphous at higher RH levels, which is fully described by a phenomenological phase transformation model. Furthermore, all fibers display cyclic repeatability (shape memory), increased swelling for longer PEG chains and lower RH rate, and disappearance of sub‐millimeter‐sized tube‐like voids after wetting.

Influence of nest box design on internal microclimate: Comparisons of plastic prototypes

AbstractHollow‐dependent fauna are declining worldwide, due primarily to the widespread clearing of hollow‐bearing trees. Artificial cavities such as timber and plywood boxes are commonly used to increase hollow availability, yet there is increasing evidence that they are poor facsimiles of natural cavities, characterized by lower insulative properties and a shorter field life. We evaluated whether plastic materials could create a nest box with a stable thermal profile that more closely resembles the complex shapes and textures of natural tree hollows while containing fewer mechanical joins that represent potential failure points when installed. We developed three sets of prototype nest boxes comprising various combinations of plastic density (10%, 25% and 50%), insulation (single vs. double wall with or without sawdust between them), nesting chamber (with or without timber inserts) and bedding (with or without decomposed heartwood) and compared their thermal performance in a temperature‐controlled laboratory to compare internal temperature and relative humidity. We found double‐walled plastic nest box with an internal timber‐lined chamber was best able to buffer ambient temperature fluctuations, consistently recording internal temperatures of 6+°C below maximum ambient temperature, maintaining high levels of relative humidity (76%–92%) when furnished with decomposed timber heartwood. This design also performed better during a simulated hot day; internal temperatures exhibiting twice the lag time of single‐walled designs, noting that plastic density had little influence on internal conditions. While the recruitment and protection of hollow‐bearing trees must be a priority, this work shows significant potential in improving the design and functionality of artificial hollows that are critical to the conservation of hollow‐dependent species.

Uptake and reactivity of acetic acid on Gobi dust and mineral surrogates: A source of oxygenated volatile organic compounds in the atmosphere?

The uptake of acetic acid (AcA) on natural Gobi dust is studied at room temperature and in the relative humidity range (<0.01–95% RH) using zero air as bath gas. The experiments were carried out in a U-shaped reactor coupled to a Selected-Ion Flow-Tube Mass Spectrometer (SIFT-MS) for gas-phase monitoring. The initial uptake coefficient, γ0, of AcA is found to decrease with RH according to the following expression γ0=γdry−(1.3×10−8)RH0.42, indicating a competition between AcA and water molecules for the same adsorption sites. AcA can be adsorbed both reversibly and irriversibly on Gobi dust. Interestingly, we evidenced that AcA uptake is reactive, especially at high levels of relative humidity (>30%) leading to the formation of oxygenated volatile organic compounds (OVOCs), such as methanol, acetaldehyde, and acetone. This is the first experimental study reporting the reactivity of AcA on natural mineral dust under ambient temperature and dark conditions. To unravel the kinetics, the uptake behavior, and reactivity of AcA on Gobi we also investigate the uptake of AcA on various mineral surogates SiO2, Al2O3, CaCO3, TiO2, Fe3O4. The results of the current study demonstrate the interest of studying heterogeneous processes at typical atmospheric levels of RH. Moreover we estimate that under atmospherically-relevant conditions, around 4% of the adsorbed AcA leads to OVOCs formation pointing at an unexplored but significant atmospheric process.

Effect of relative humidity on the quality and safety of peeled almond kernels (Prunus dulcis Mill.) during simulated maritime transport/storage.

Long-term transport and storage of peeled almonds under unsuitable conditions may cause the product's rejection. To get knowledge in this topic, peeled almonds were stored at 25°C and 60, 70, and 80% relative humidity (RH). The maintenance of high RH (80%) caused some visual defects after 4 months. Even though the 60, 70, and 80% RH did not clearly affect the production of primary and secondary products formed in the lipid oxidation during the 6 months of storage, sometimes an increase in the values of the specific extinction at the wavelength of 268nm (K268 ) was observed at 80% RH, suggesting the occurrence to some extent of secondary oxidation. Concerning microbial counts, the almonds stored at 60 and 70% RH presented a satisfactory microbial quality until 6 months; however, at 80% RH, the mold counts were higher than the reference values after 2 months. Several mycotoxins were detected at low levels, including aflatoxins B1 and G1, although some showed higher amounts at 80% RH. In general, it is recommended that almond producers and industrials should consider the use of low RH (<80%) for maritime transport and long-term storage of almond kernels. PRACTICAL APPLICATION: High levels of relative humidity during storage/transport of almond kernels favor fungal growth, mycotoxin production, and secondary oxidation (rancidity). It is recommended to keep the almond kernels under low RH(<80%) in maritime transport and long storage, especially in tropical countries.

Orchard microclimate, tree water uptake and sweet cherry fruit quality under protected cropping.

Protected cropping systems (PCS) de-risk adverse climatic effects in intensive horticultural production but alter the growing environment. The objectives of this study were to investigate the effects of modern, commercial-scale PCS on sweet cherry orchard microclimate, tree water uptake and fruit quality. Sap flow sensors and weather stations were positioned at four locations under a 21 ha PCS at varying elevations (125, 114, 111, 102 m above sea level) and distances from the block boundary (105, 75, 60 or 50 m, referred to hereafter as Locations 1 to 4, respectively). Generalised additive models (GAMs) were used to predict the effect of individual climate parameters (temperature, relative humidity, solar radiation and wind speed) on tree sap flow at each of the four locations. Average and maximum temperatures and average minimum relative humidity (RH) were higher (15.9°C, 26.1°C and 49.0%) at locations with higher elevations and located further from the PCS boundary (locations 1 and 2) in contrast to locations at lower elevations and closer proximity to the PCS boundary (locations 3 and 4) (15.4°C, 24.6°C and 48.1%). Predicted sap flow was strongly correlated (r2 = 0.92) with time across the four locations under the PCS. GAMS modelling indicated that the hourly water uptake by trees within close proximity to the block boundary (locations 3 and 4) responded with greater intensity to increases in temperature and reductions in relative humidity, taking up on average 0.15 L h-1 (at temperatures >30°C) and 0.08 L h-1 (at RH<50%), respectively, in contrast to trees further under the PCS (locations 1 and 2) where average tree water uptake was 0.08 and 0.04 L h-1 at temperatures >30°C and RH<50%, respectively. Highest average predicted hourly tree sap flow was associated with high wind speeds (0.67 L h-1) and low relative humidity levels (0.61 L h-1). Fruit harvested from locations further from the PCS boundary had significantly higher dry matter content (18.2%), total soluble solids (17.8%) and compression firmness (311.3 g mm-1) in contrast to fruit closer to the PCS boundaries (16.1%, 15.7% and 258.3 g mm-1). This study provides greater understanding of the effects of PCS on microclimate and consequences for tree water uptake and fruit quality.