Low Relative Humidity Research Articles

Joint effects of temperature and humidity with PM2.5 on COPD

BackgroundParticulate matter less than 2.5 microns in aerodynamic diameter (PM2.5) is a significant air pollutant known to adversely affect respiratory health and increase the incidence of chronic obstructive pulmonary disease (COPD). Furthermore, climate change exacerbates these impacts, as extreme temperatures and relative humidity (RH) levels can intensify the effects of PM2.5. This study aims to examine the joint effects of PM2.5, temperature, and RH on the risk of COPD.MethodsA case–control study was conducted among 1,828 participants from 2017 to 2022 (995 COPD patients and 833 controls). The radial basis function interpolation was utilized to estimate participants' individual mean and differences in PM2.5, temperature, and RH in 1-day, 7-day, and 1-month periods. Logistic regression models examined the associations of environmental exposures with the risk of COPD adjusting for confounders. Joint effects of PM2.5 by quartiles of temperature and RH were also examined.ResultsWe observed that a 1 µg/m3 increase in PM2.5 7-day and 1-month mean was associated with a 1.05-fold and 1.06-fold increase in OR of COPD (p < 0.05). For temperature and RH, we observed U-shaped effects on OR for COPD with optimal temperatures identified as 21.2 °C, 23.8 °C, and 23.8 °C for 1-day, 7-day, and 1-month mean temperature, respectively, and optimal RH levels identified as 73.8%, 76.7%, and 75.4% for 1-day, 7-day, and 1-month mean RH, respectively (p < 0.05). The joint effect models show that high temperatures (> 23.5 °C) and both extremely low (69.3%) and high (80.9%) RH levels generally exacerbate the effects of PM2.5 on OR for COPD, especially over longer exposure durations.ConclusionThe joint effects of PM2.5, temperature, and RH on the risk of COPD underscore the importance of air pollution control and comprehensive research to mitigate COPD risk in the context of climate change.

Positrons as microprobes to study water-dependent free volume of wood cell walls: a preliminary study

Abstract Positron annihilation lifetime spectroscopy (PALS) was employed to study the water-dependent free volume characteristics of wood cell walls in earlywood and latewood of loblolly pine (Pinus taeda). Measurements were conducted across relative humidity levels (1–80% RH) at room temperature, demonstrating good reproducibility and consistency with polymer science principles. The Tao-Eldrup model was applied to the measured ortho-positronium lifetimes to estimate the mean sizes of free volume elements in wood cell walls. At low relative humidity (below ~ 11%), water absorption resulted in antiplasticization, evidenced by a decrease in mean free volume element sizes. As relative humidity increased, water started acting as a plasticizer, causing the free volume elements to expand. While dry cell walls showed no significant differences in free volume element sizes between earlywood and latewood, earlywood exhibited larger mean free volume element sizes at all higher relative humidity levels. At higher relative humidity levels (above ~ 70% RH), the ortho-positronium lifetimes of cell wall free volume elements overlapped with those of liquid water, indicating PALS cannot provide reliable free volume information at higher cell wall moisture contents. Interpreting the intensity of ortho-positronium annihilation was complicated by the possibility of water inhibiting ortho-positronium formation in wood cell walls.

Risk effects of environmental factors on human brucellosis in Aksu Prefecture, Xinjiang, China, 2014–2023

The context of rapid global environmental change underscores the pressing necessity to investigate the environmental factors and high-risk areas that contribute to the occurrence of brucellosis. In this study, a maximum entropy (MaxEnt) model was employed to analyze the factors influencing brucellosis in the Aksu Prefecture from 2014 to 2023. A distributed lag nonlinear model (DLNM) was employed to investigate the lagged effect of meteorological factors on the occurrence of brucellosis. A total of 17 environmental factors were identified as affecting the distribution of brucellosis to varying degrees. The largest contributing was the normalized difference vegetation index (NDVI), followed by gross domestic product (GDP), and then meteorological factors such as average temperature, average relative humidity, and average wind speed. The receiver operating characteristic (ROC) curve demonstrated that the MaxEnt model exhibited a high degree of predictive efficacy, with an area under the curve (AUC) value of 0.921. The impact of high temperature (25℃ with a 2-month lag, RR = 3.130, 95% CI 1.642 ~ 5.965), low relative humidity (28% with a 2.5-month lag, RR = 1.795, 95% CI 1.298 ~ 2.483), and low wind speed (1.9 m/s with a 0-month lag, RR = 2.408, 95% CI 1.360 ~ 4.264) are the most significant meteorological factors associated with the incidence of brucellosis. The trends in the impact of extreme meteorological conditions on the spread of brucellosis were found to be generally consistent. Stratified analyses indicated that males were more affected by meteorological factors than females. The prevalence of brucellosis is influenced by a range of socio-economic and meteorological factors, and a multifaceted approach is necessary to prevent and control brucellosis.

Ultrafast Detection of ppb-Level NH3 Gas at Room Temperature Using CuO Nanoparticles Decorated AlN-Based Surface Acoustic Wave Sensor.

Rational design of heterostructure (HS)-based surface acoustic wave (SAW) smart gas sensors for efficient and accurate subppm level ammonia (NH3) detection at room temperature (RT) is of great significance in environmental protection and human safety. This study introduced a novel HS composed of an AlN-based SAW resonator and CuO nanoparticles (NPs) as a chemical interface for NH3 detection at RT (∼26 °C). The structural, morphological, and chemical compositions were detailly investigated, which demonstrates that the CuO/AlN HS was successfully formed via interfacial modulation. The CuO/AlN HS SAW sensor exhibited a significant positive frequency shift of 52.60 kHz in response to 100 ppm of NH3, which is 4.8 times higher than that of the as-grown AlN SAW sensor. Additionally, the CuO/AlN HS SAW sensor exhibited ultrafast response/recovery times of 5/25 s, a remarkably low limit of detection (LOD) of 24 ppb, and excellent long-term stability and selectivity. These results are attributed to the high porosity and defect sites of CuO NPs, which enhanced charge transfer at the heterointerface, as well as decreased mass loading and conductivity effects. The CuO/AlN HS SAW sensor also demonstrated distinct frequency responses to 100 ppm of NH3, under varying relative humidity (RH): a positive shift at low RH (5%-10%) due to increased conductivity, and a negative shift at high RH (20%-80%) due to enhanced mass loading. These NH3 gas sensing characteristics of the CuO/AlN HS SAW sensor were validated through X-ray photoelectron spectroscopy band diagram analysis and resistive-type gas sensing measurements. These findings highlight the potential of the integrating metal oxide with nitride semiconductors for advanced SAW-based gas sensing technology in environmental and industrial applications.

Carbonation under Varying Humidity Conditions: A 3D Micro-Scale Kinetic Monte Carlo Approach.

This paper investigates the impact of varying humidity conditions on the carbonation depth in hardened cement paste using a 3-dimensional microscale kinetic Monte Carlo (kMC) approach. The kMC algorithm effectively simulates the carbonation process by capturing the interplay between CO2 diffusion and relative humidity at the microscale, providing insights into macro trends that align with historical models. The study reveals that the maximum carbonation depth is achieved at relative humidity levels between 55 and 65%, where the balance between water and CO2 diffusion is optimized. At lower relative humidity levels (<55%), a lower carbonation depth is observed. Conversely, at higher relative humidity levels (>65%), increased water content impedes CO2 diffusion, resulting in reduced carbonation depth for cement paste. The kMC model demonstrates a parabolic relationship between relative humidity and carbonation depth. Time series analysis shows that Fick's law is consistently followed, with carbonation depth following the relationship x = k√t at constant relative humidity. The kMC also breaks down the event cycle which shows that after an equilibrium (in terms of rate of events) is achieved between CO2 and H2O at a relative humidity of 75%, a shift occurs in the dominance from reactive to transport processes at a relative humidity of 85%. These findings highlight the importance of humidity in influencing carbonation rates on the one hand and demonstrate the effectiveness of the kMC approach in simulating these complex interactions at the microscale on the other hand.

Measurement report: Analysis of aerosol optical depth variation at Zhongshan Station in Antarctica

Abstract. Our understanding of aerosol optical depth (AOD) in Antarctica remains limited due to the scarcity of ground observation stations and limited daylight days. Utilizing data from the CE318-T photometer spanning January 2020 to April 2023 at Zhongshan Station, we analyzed the seasonal, monthly, and diurnal variations in AOD and the Ångström exponent (AE). AOD median values increased from spring (0.033) to winter (0.115), while AE peaked during summer (1.010) and autumn (1.034), declining in winter (0.381), indicating a transition in dominant aerosol particle size from fine to coarse mode between summer and winter. Monthly mean AOD variation closely paralleled the proportion of AE &lt; 1, suggesting fluctuations in coarse-mode particle proportions drive AOD variation. The high AOD values during winter and spring were associated with an increased contribution of coarse-mode particles, while high AOD values during summer and autumn were associated with the growth of fine-mode particles. We observed a peak in AOD (∼ 0.06) at 14:00 local time (LT) at Zhongshan Station, possibly associated with a slight decrease in boundary layer height (BLH). Additionally, higher (lower) wind speeds corresponded to lower (higher) AOD values, indicating the diffusion (accumulation) effect. The temperature and AOD showed an insignificant positive correlation (R = 0.22, p = 0.40), and relative humidity exhibited a significant negative correlation with AOD (R = −0.59, p = 0.02). Backward trajectory analysis revealed that coarse particles from the ocean predominantly contributed to high AOD daily mean values, while fine particles on low-AOD days originated mainly from the air mass over the Antarctic Plateau. This study enhances the understanding of the optical properties and seasonal behaviors of aerosols in the coastal Antarctic. Specifically, AOD measurements during the polar night address the lack of validation data for winter AOD simulations. Additionally, we revealed that lower wind speeds, higher temperatures, and lower relative humidity contribute to increased AOD at Zhongshan Station, and air masses from the ocean significantly impact local AOD levels. These findings help us infer AOD variation patterns in the coastal Antarctic based on meteorological changes, providing valuable insights for climate modeling in the context of global climate change.

Thermodynamic Analysis of Adsorption-Based Atmospheric Water Harvesting using Various Adsorbents in Iraqi Conditions

This study investigates the thermodynamic performance of various adsorbent materials used in adsorption-based atmospheric water harvesting (AWH), with a focus on their application in arid regions, such as Iraq. While significant advancements have been made in developing adsorbents capable of capturing water at low humidity levels, the lack of detailed thermodynamic analysis has hindered optimal operational conditions for these materials. The study evaluates the thermodynamic efficiencies of MOF-808, MCM-41, and COF-432, comparing their performance with other materials like MOF-801, MOF-803, and Ni2Cl2BTDD. Key findings indicate that source temperature and outlet relative humidity significantly influences system efficiency, with higher source temperatures generally improving thermal efficiency. However, lower outlet relative humidity, especially at higher temperatures, can further enhance system efficiency, emphasizing the importance of effective humidity control. Additionally, the study highlights that Iraq’s elevated ambient temperatures may exacerbate efficiency losses due to higher thermal sink temperatures, underscoring the need for adaptive design strategies. The performance of various adsorbents was found to be highly material-dependent, with certain adsorbents offering superior thermal and second-law efficiencies under specific conditions. This study offers crucial insights into optimizing adsorbent selection and system design for AWH systems, particularly in challenging climates.

Corrosion Mechanism of Press-Hardened Steel with Aluminum-Silicon Coating in Controlled Atmospheric Conditions

The effect of various atmospheric parameters on the corrosion mechanism of press-hardened steel (PHS) coated with Al-Si (AS) was studied. Quantitative models of the composition of soluble and stable corrosion products were developed. A high chloride concentration led to a localized corrosion due to the presence of cracks in the coating. Increased corrosion resistance of silicon-rich Al8Fe2Si and AlFe at the expense of the Al5Fe2 phase with low silicon content was shown. Under low-chloride-deposition conditions, the coating exhibited good corrosion resistance and provided sufficient protection to the underlying steel. The formation of more local anodes and cathodes under conditions of lower relative humidity led to a reduction in the depth of corrosion pits in the steel substrate. Constant high relative humidity and sulphate deposits on the surface were critical for the acceleration of steel corrosion in coating cracks.

The effect of short-term exposure to air pollution on the admission of ischemic stroke and its interaction with meteorological factors.

The aim of this study was to investigate the associations, potential effects, and interactions between short-term exposure to air pollution and the risk of ischemic stroke (IS). An ecological study. Daily data on IS incidents, air pollution, and meteorological conditions were collected from 2017 to 2021 in Gannan. A time-stratified case-crossover design, combined with a distributional lag nonlinear model, was employed to analyze the relationship between air pollution exposure and the admission of IS. Additionally, the interaction between air pollutants and meteorological factors was examined using bivariate response surface modeling. The study also conducted stratified analyses based on gender, age, marital status, medical insurance purchase status, and season of admission. In the single lag day structure, extremely low levels of PM2.5 (RR=1.11, 95% CI: 1.03-1.20) and PM10 (RR=1.10, 95% CI: 1.02-1.20) peaked on lag 3. Conversely, extremely high levels of NO2 (RR=1.05, 95% CI: 1.01-1.10), CO (RR=1.19, 95% CI: 1.03-1.37), and extremely low levels of O3 (RR=1.09, 95% CI: 1.01-1.19) exhibited a greater relative risk on lag 4. In the cumulative lag-day structure, extremely high levels of NO2 exhibited the most significant hazard effect at lag 05 (RR=1.27, 95% CI: 1.01-1.52), while extremely low levels of CO at lag 02 (RR=1.15, 95% CI: 1.05-1.24) and extremely low levels of O3 at lag 01 (RR=1.20, 95% CI: 1.04-1.40) also demonstrated notable associations. In the subgroup stratum, the association between air pollution and IS was found to be more significant in patients who were male, aged <65 years, married, had medical insurance, and were admitted during the cold season. The lowest number of IS hospitalisations occurred under low relative humidity conditions alongside increasing concentrations of CO. Short-term exposure to air pollution was positively associated with an increased risk of IS. This association was influenced by factors such as being male, aged <65 years, married, having medical insurance, and admissions during the cold season. Additionally, an interaction was observed between air pollutants and meteorological factors. These findings carry significant public health implications for the prevention of IS.

Long‐Lasting Moisture Energy Scavenging in Dry Ambient Air Empowered by a Salt Concentration‐Gradient Cationic Hydrogel

AbstractConverting ambient moisture into electric power is attractive as a next‐generation energy harvesting technology, serving as a countermeasure to overwhelming energy demands due to its sustainability and ubiquitous nature. However, achieving a long‐lasting and high density of electrical power generation at low humidity is challenging. Here, synergizing a water flow and an auxiliary anion migration in tandem with an embedded ion flow in a salt concentration‐gradient cationic gel, these challenges are tackled and developed a moisture‐activated electricity generator (MEG) with longevity (&gt;50 days), low energy loss, and adequate power of 13.8 mW m−2 at low (30%) relative humidity. Witha stacking strategy with combinations of serial and parallel configurations, the electrical output of the MEG module can cover practical electric devices with a broad range of power consumption, unveiling the potential of MEG to power practical appliances sustainably and omnipresently.

Weather and glufosinate efficacy; a retrospective analysis looking forward to the changing climate

Abstract Foliar-applied postemergence applications of glufosinate are often applied to glufosinate-resistant crops to provide nonselective weed control without significant crop injury. Rainfall, air temperature, solar radiation, and relative humidity near the time of application have been reported to affect glufosinate efficacy. However, previous research may have not captured the full range of weather variability to which glufosinate may be exposed to prior to or following application. Additionally, climate models suggest more extreme weather will become the norm, further expanding this weather range glufosinate can be exposed to. The objective of this research was to quantify the probability of successful weed control (efficacy ≥85%) with glufosinate applied to some key weed species across a broad range of weather conditions. A database of &gt;10,000 North American herbicide evaluation trials was used in this study. The database was filtered to include treatments with a single POST application of glufosinate applied to waterhemp (Amaranthus tuburculatus (Moq.) J. D. Sauer), morningglory species (Ipomoea spp.), and/or giant foxtail (Setaria faberi Herm.) &lt;15cm in height. These species were chosen because they are well represented in the database and listed as common and troublesome weed species in both corn (Zea mays L.) and soybean [Glycine max (L.) Merr.] (Van Wychen 2020, 2022). Individual random forest models were created. Low rainfall (≤20 mm) over the five days prior to glufosinate application was detrimental to the probability of successful control of A. tuburculatus and S. faberi. Lower relative humidity (≤70%) and solar radiation (≤23 MJ m-1 day-1) the day of application reduced the probability of successful weed control in most cases. Additionally, the probability of successful control decreased for all species when average air temperature over the first five days after application was ≤25C. As climate continues to change and become more variable, the risk of unacceptable control of several common species with glufosinate is likely to increase.

In Situ Quantification of Transition Metal Cation Leaching from a Pt-Alloy Cathode Catalyst in a PEM Fuel Cell

The application of Pt-alloy cathode catalysts for proton exchange membrane fuel cells (PEMFCs) is hampered by the leaching of the alloyed transition metal into the ionomer phase of the membrane electrode assembly (MEA). To date, accelerated stress tests used to assess the degradation of Pt-alloy catalysts lack non-destructive, facile diagnostics to quantify transition metal leaching in an operating PEMFC. Here, we present a method based on electrochemical impedance spectroscopy that exploits the high sensitivity of the high frequency resistance (HFR) at low relative humidity (RH) to quantify transition metal cation contamination. A series of model MEAs with varying fractions of protons intentionally exchanged by Co2+ cations was fabricated. Based on these, we identified the HFR at 30% RH and zero current (i.e., at a homogenous Co2+ distribution in the ionomer phase) as a robust measure of Co2+ contamination. A calibration curve that correlates the HFR at 30% RH to the fraction of protons displaced by Co2+ in the model MEAs could be established, which then allowed quantitative tracking of the Co leached from a PtxCo/C cathode catalyst, both at the beginning-of-test (∼6%) and after 100,000 voltage cycles (∼30%). Capabilities and limitations of this method for Pt-alloy catalyst testing are discussed.

DISINFECTION BY HYDROGEN PEROXIDE AT LOW CONCENTRATION IN AIR: THE KEY ROLE OF CONDENSATION.

Gazeous hydrogen peroxide (H2O2) is commonly used for disinfection of room surfaces or sterilization of medical devices. Disinfection and sterilization processes are controlled by mean values measured at sterilizer chamber or room level. However, the surface phenomena (adsorption/ condensation) taking place on inoculum are essential and still not well-known. In the present study, a solution of water and H2O2 is sprayed in a room disinfection system (Glosair 400, ASP) for 12min. Condensation mass, H2O2 concentration, relative humidity (RH), macro zoom observations and inactivation kinetics of various microorganisms (Staphyloccocus aureus, Pseudomonas aeruginosa Candida albicans, Aspergillus niger) are reported. Macro-zoom observations reveal condensation and bubbling activities. Microbial inactivation is found optimal at low initial RH, corresponding to high H2O2 vapor concentration and low condensed mass. H2O2 concentration in the condensate is high and probably boosted by fractional condensation. In surface disinfection processes, inactivation of microorganisms occurs in presence of condensation although excessive condensation, due to high initial RH conditions or the presence of salt, decreases the microbial inactivation efficiency by dilution. While the present experimental conditions differ from those prevailing in H2O2 sterilization (59 % H2O2 under vacuum) or industrial disinfection processes (30% H2O2 at atmospheric pressure), they are partially transposable.

Cost-effective drying methods for edible bird’s nest hydrolysate: Impact on nitrite levels and sialic acid content

To produce powdered edible bird’s nest hydrolysate (EBNH), a significant amount of water must be removed after hydrolysis to improve the product’s stability, extend shelf life, and reduce transportation and storage costs. This study investigates the application of cool-air and hot-air drying methods, with a particular focus on strategies suited for small and medium-sized enterprises (SMEs). Cool-air drying was performed at 17 °C using a fan and air conditioner, while hot-air drying was conducted at 55 °C and 65 °C using a dehydrator. The study evaluated drying time, as well as the quality, moisture content, nitrite levels, total sialic acid content, and antioxidant activity of EBNH produced by each method. The quality, cost, and feasibility of these methods were compared with freeze-drying and spray-drying techniques from previous studies. Results showed that higher temperatures and lower relative humidity improved drying efficiency, with hot-air drying at 65 °C requiring the shortest drying time. Chemical analysis revealed significant differences in nitrite and total sialic acid content: cold-air-dried samples had higher nitrite levels, while hot-air drying at 65 °C produced the highest total sialic acid content. Cost and feasibility assessments demonstrated that hot airdrying at 65 °C was the most efficient and cost-effective method. This method is especially advantageous for SMEs due to its balance of efficiency, affordability, and ease of implementation, making it ideal for smaller-scale operations.

High-Performance and Anti-Freezing Moisture-Electric Generator Combining Ion-Exchange Membrane and Ionic Hydrogel.

Moisture-electric generators (MEGs), which convert moisture chemical potential energy into electrical power, are attracting increasing attention as clean energy harvesting and conversion technologies. However, existing devices suffer from inadequate moisture trapping, intermittent electric output, suboptimal performance at low relative humidity (RH), and limited ion separation efficiency. This study designs an ionic hydrogel MEG capable of continuously generating energy with enhanced selective ion transport and sustained ion-to-electron current conversion at low RH by integrating an ion-exchange membrane (IEM-MEG). A single IEM-MEG exhibits a maximum open-circuit voltage (VOC) of 0.815 V and a short-circuit current (ISC) of 101 µA at 80% RH. Even at a low RH of 10%, a stable VOC of 0.43 V and ISC of 11 µA can be generated. Moreover, the antifreeze performance of the device is improved by adding LiCl, which significantly expands its operational range in low-temperature environments. Finally, a simple series-parallel connection of six IEM-MEGs can yield an enhanced VOC of 4.8 V and a ISC of ≈0.6 mA, and the scalable units can directly power commercial electronics. This study provides new insights into the design of MEGs that will advance the development of green energy conversion technologies in the future.

Superprotonic conduction of {NBu4–n(enOH)n}[MnCr(ox)3] (Bu = n-butyl; enOH = 2-hydroxyethyl; n = 1–3) in successive multiplication of hydroxyl proton-carrier in the cation

Abstract Proton conduction in a new series of two-dimensional metal-organic frameworks, {NBu4–n(enOH)n}[MnCr(ox)3] (n = 1: (B3O)MnCr; n = 2: (B2O2)MnCr; n = 3: (BO3)MnCr), was studied with respect to their molecular and network structures. Crystallographic studies revealed that (B3O)MnCr consisted of honeycomb-based oxalate-bridged bimetallic [MnCr(ox)3]– sheets with {NBu3(enOH)}+ ions intercalated in between. The enOH group was inserted into the cavity of the honeycomb sheet and the hydroxy group protruded out of the cavity to form a hydroxyl-face on the sheet, which played a pivotal role in proton conduction via the vehicle mechanism under low relative humidity (RH). Under high RH conditions, water adsorption modified the hydroxyl-face such that a hydrogen-bonding network was formed, which mediated proton transfer via the Grotthuss mechanism. The proton conductivities (σ) of (B3O)MnCr and (B2O2)MnCr at 25 °C under 95% RH were 6.2 × 10–5 and 6.7 × 10–4 S cm–1, respectively, which increase to 1.7 × 10–4 and 2.0 × 10–3 S cm–1, respectively, with increasing the temperature to 50 °C. (BO3)MnCr deliquesces under the same conditions; however, the σ value under 70% RH was higher than those of (B3O)MnCr and (B2O2)MnCr, primarily because of the further introduction of the enOH group in the cation.

New Composite Packaging Material from Edible Oil By-Product Coated with Paraffin Wax for Dry Apricot Slice Packing Under a Modified Atmosphere.

Composite biopolymer hydrogel as food packaging material, apart from being environmentally favorable, faces high standards set upon food packaging materials. The feature that favors biopolymer film application is their low gas permeability under room conditions and lower relative humidity conditions. However, most biopolymer-based materials show high moisture sensitiveness and limited water vapor permeability, which limits their application for food packaging. In this paper, a new packaging material derived from an edible oil industry byproduct (pumpkin oil cake) coated with a thin layer of paraffin wax was obtained. Compared to the film without wax coating, the new material showed reduced water sensitivity and significantly reduced water vapor transmission rate (56.98 ± 7.42 g/m2 24 h). The new material was tested for packing dry apricot slices under a modified atmosphere (100% N2). Gas composition in PuOC/wax pouches' headspace was minimally changed during 105 days of storage. The low moisture content (6.76-10.60%) of dried apricot slices was preserved throughout the storage period (p > 0.05), as well as high rehydration power (65-75%). Changes in sensorial properties during storage were minimal. Total phenol content was minimally reduced during storage, followed by antioxidant activity (FRAP and ABTS trial). The microbial profile of dried apricot slices showed that a safe product was obtained throughout the storage. Considering the results, the functionality of new material for packing dry apricots under a modified atmosphere was proven.

Entrainment, detrainment and dilution of dry and moist atmospheric thermals

Abstract This study examines entrainment, detrainment, and dilution of dry and moist (cloud) atmospheric thermals in large-eddy simulations. In a neutrally stable environment (with respect to dry dynamics), moist thermals have an increase in radius R with thermal height zt (α ≡ dR/dzt) about 4 times smaller compared to dry thermals when density stratification is considered, and ∼2.4 times smaller without density stratification (i.e., applying the Boussinesq approximation). An analytic expression relating α to several dimensionless parameters is derived from the thermal impulse-circulation relation to clarify the factors impacting α. This expression shows that the difference in buoyancy structure between moist and dry thermals, with buoyancy concentrated in the central cores of moist thermals owing to latent heating, explains their smaller spreading rates. Individual contributions of entrainment and detrainment are analyzed using a direct parcel-based approach in the simulations. Moist thermals have similar fractional detrainment but much smaller fractional entrainment rates compared to dry thermals, consistent with the differences in α. Despite having smaller α, moist thermals are similarly dilute (quantified by a passive tracer) as dry thermals because of their greater mixing efficiency with the environment. Thus, moist thermals are substantially dilute but expand much less in size/volume as they rise compared to dry thermals. α values for moist thermals in (dry) neutral and statically stable environments are similar, but fractional entrainment and especially detrainment rates are greater in the stable environment. Large detrainment rates are associated with a breakdown of the broader thermal vortex ring structure, especially with low environmental relative humidity, attributed in part to evaporation and buoyancy reversal.

Habitat Suitability Modelling for the Red Dwarf Honeybee (Apis florea (Linnaeus)) and Its Distribution Prediction Using Machine Learning and Cloud Computing

Apis florea bees were recently identified in Egypt, marking the second occurrence of this species on the African continent. The objective of this study was to track the distribution of A. florea in Egypt and evaluate its potential for invasive behaviour. Field surveys were conducted over a 2-year period, resulting in the collection of data on the spatial distribution of the red dwarf honeybees. A comprehensive analysis was performed utilizing long-term monthly temperature and rainfall data to generate spatially interpolated climate surfaces with a 1-km resolution. Vegetation variables derived from Terra MODIS were also incorporated. Furthermore, elevation data obtained from the Shuttle Radar Topography Mission were utilized to derive slope, aspect, and hillshade based on the digital elevation model. The collected data were subject to resampling for optimal data smoothing. Subsequently, a random forest model was applied, followed by an accuracy assessment to evaluate the classification output. The results indicated the selection of the mean temperature of coldest quarter (bio11), annual mean temperature (bio01), and minimum temperature of coldest month (bio06) as temperature-derived parameters are the most important parameters. Annual precipitation (bio12) and precipitation of wettest quarter (bio16) as precipitation parameters, and non-tree vegetation parameter as well as the elevation. The calculation of the Habitat Suitability Index revealed that the most suitable areas, covering a total of 200131.9 km2, were predominantly situated in the eastern and northern regions of Egypt, including the Nile Delta characterized by its fertile agricultural lands and the presence of the river Nile. In contrast, the western and southern parts exhibited low habitat suitability due to the absence of significant green vegetation and low relative humidity.

Quasi-Steady Water Droplet Heat- and Mass-Transfer With Ventilation, Blowing, and Radiation

Abstract A quasi-explicit analytical model of quasi-steady (QS) water droplet heat- and mass-transfer, including radiation, in a prescribed gaseous environment with velocity slip, i.e., gas flow around the droplet, and high mass-transfer-rate blowing effects has been developed. The model is an extension of an atmospheric science model used for cloud and fog droplets in dilute and near-saturation conditions with negligible velocity slip (ventilation flow) and blowing. The new model includes the effects of ventilation flow, blowing, and change in relative humidity or supersaturation across the diffusion layer surrounding the droplet. Comparisons show significant improvement in accuracy over the conventional model, particularly for conditions of low relative humidity, low pressure, and high radiative flux.