Hot Days Research Articles

Historical land use and land cover change reduced the temperature of cold extremes more than that of hot extremes

<p>The impact of historical land use and land cover change (LULCC) on the mean climate has been extensively studied, but its impact on temperature extremes is not well understood. This study investigates the biophysical effect of LULCC on temperature extremes using two sets of model simulations �C one with land use fixed at 1850 level and the other with historical LULCC from 1850 to 2014. We find that the historical LULCC has two asymmetric effects: (i) it decreases the temperature of coldest day (�C0.56 �� 0.23 K; mean �� std. error) more than that of the hottest day (�C0.21 �� 0.07 K) at the mid-latitudes of northern hemisphere; and (ii) it has a stronger impact in the mid-latitudes of northern hemisphere relative to the tropical region. These changes result largely from an indirect effect of LULCC via changes in clouds, circulations, and the downward longwave radiation. We stress that the indirect effects from climate feedback of LULCC should be considered when implementing reforestation policy.</p>

Hot climate, hot koalas: the role of weather, behaviour and disease on thermoregulation.

Thermoregulation is critical for endotherms living in hot, dry conditions, and maintaining optimal core body temperature (Tb) in a changing climate is an increasingly challenging task for mammals. Koalas (Phascolarctos cinereus) have evolved physiological and behavioural strategies to maintain homeostasis and regulate their Tb but are thought to be vulnerable to prolonged heat. We investigated how weather, behaviour and disease influence Tb for wild, free-living koalas during summer in north-west New South Wales. We matched Tb with daily behavioural observations in an ageing population where chlamydial disease is prevalent. Each individual koala had similar Tb rhythms (average Tb = 36.4 ± 0.05°C), but male koalas had higher Tb amplitude and more pronounced daily rhythm than females. Disease disrupted the 24-hr circadian pattern of Tb. Koala Tb increased with ambient temperature (Ta). On the hottest day of the study (maximum Ta = 40.8°C), we recorded the highest (Tb = 40.8°C) but also the lowest (Tb = 32.4°C) Tb ever documented for wild koalas, suggesting that they are more heterothermic than previously recognized. This requires individuals to predict days of extreme Ta from overnight and early morning conditions, adjusting Tb regulation accordingly, and it has never been reported before for koalas. The large diel amplitude and low minimum Tb observed suggest that koalas at our study site are energetically and nutritionally compromised, likely due to their age. Behaviour (i.e. tree hugging and drinking water) was not effective in moderating Tb. These results indicate that Ta and koala Tb are strongly interconnected and reinforce the importance of climate projections for predicting the future persistence of koalas throughout their current distribution. Global climate models forecast that dry, hot weather will continue to escalate and drought events will increase in frequency, duration and severity. This is likely to push koalas and other arboreal folivores towards their thermal limit.

The role of trees in enhancing outdoor thermal comfort during warm season in a sub-humid climate. Case: Souk Ahras city

Enhancing the quality of life for people in urban areas necessitates focusing on outdoor thermal comfort OTC. This study examines the role and impact of urban vegetation, particularly trees, in improving the meteorological conditions that characterize the urban microclimate in order to enhance OTC, focusing on two public spaces in Souk Ahras city, characterised by in situ measurement campaigns and modelling during hot summer day. In situ campaigns were carried out to measure climatic data (air temperature, relative humidity and wind speed), and to collect data on vegetation (trees) and building geometry, which were used in numerical modelling to calculate the various thermal indices: SVF, Tmrt, PET and OUT_SET using the Rayman microclimatic model. The results show that the trees at each intervention site can reduce the average daily air temperature of 0.376?C to 1.04?C and an enhancement of thermal comfort in terms of average radiant temperature Tmrt of 2.08?C to 5.85?C and equivalent physiological temperature PET of 1.91?C to 3.84?C and standard equivalent temperature OUT_SET of 1.72?C to 2.86?C. in the knowledge that trees also help to reduce the Skye view factor, an essential geometric measure for assessing the thermal environment, which proves that the effect of shading and evapotranspiration provided by trees mainly contribute to enhancing outdoor thermal comfort during the warm season.

Is it Just Global Warming and How Much we Have Contributed to it?

If it was a Global warming the temperatures will be higher day and night, summer and winter. However, we have: 1/ very hot days and very cold nights with temperature difference reaching 300 F and 2/ very hot summers and cold winters with temperature difference reaching more than 1000 F. This means one thig – Earth’s atmosphere is becoming thinner, which makes the days and summers hotter and the nights and winters colder because the thinner atmosphere cannot hold the received heat. Also, Aurora Borealis is normally observed only in polar areas not covered by the ionosphere, which is like a doughnut around the Earth. The fact that Aurora Borealis was observed in Scotland in March 2023 means that the Earth’s ionosphere, which holds the atmosphere, is shrinking. The shrinking of the ionosphere (and the atmosphere) is caused by the way we make rain to avoid the drought – we use the ions of the ionosphere. This depleted the ionosphere, which holds the atmosphere. We need to change the way we make rain and try to replenish the ions of the ionosphere, which we have used to create rain. If we don’t do this the Earth will lose its atmosphere and will become uninhabitable.

Investigation of Temporal Trends and Spatial Patterns of Extreme Temperatures and Their Relationship to Climate Circulation Indices in Tanzania

This paper examined the spatial and temporal patterns of selected temperature extreme indices using the Mann-Kendall method (MK), the standard t-test, and the Pearson correlation analysis method. The relationship between extreme temperature events and climate circulation indices was analysed in Tanzania between 1983 and 2016 using data from 1961 to 2018. The results uncover a rise in the frequency and intensity of balmy days and nights across Tanzania. It suggests a significant increase in trends and the frequency of mild temperature index days and warm nights. It also indicates an increase in the trends for warm temperature indices (hottest days (TXx), coldest days (TNx), warm days (TX90p), tropical night (TR20), and Warm Spell Duration Indicator (WSDI); and a decrease in cold temperature indices (cold days (TX10p), cold nights (TN10p), cold days (TXn), and Cold Spell Duration Indicator (CSDI); which imply that the lower temperature was gradually decreasing more than in the past. The results further suggest that warm days and nights are significantly correlated with the Tropical Northern Atlantic Index (TNA), the Interdecadal Pacific Oscillation (IPO), the Atlantic Multidecadal Oscillation (AMO), and the El Nino-Southern Oscillation (ENSO). The circulation indices, which were found to be substantially associated with temperature extreme indices, can aid in forecasting, and may potentially serve as a foundation for future studies, particularly in the dynamics and physical mechanisms related to temperature extremes. The results presented in this paper are also vital for developing proper mitigation and adaptation measures to reduce future risks associated with extremely high-temperature events.

Controlling and Modelling a Grid Connected Photovoltaic System for Performance Investigation Purpose

The world restriction of fossil power sources reserves and its side effect on the environmental pollution have impelled strongly using the photovoltaic technology as alternative renewable energy sources. The essential problem is the difficulty of importing and installing solar panels without having a fully knowledge about its effectiveness in the climatic conditions of the university site. Hence, the motivation of this study is to investigate the operational efficiency of the PV system in the Iraqi environmental conditions by modelling, controlling, and simulating the system using MATLAB/Simulink program. The proposed model has been driven based on the principle mathematical equations that depict the behaviour of the PV solar system. The proposed model is designed to affect with the sunlight irradiance, ambient temperature, AC loss, DC loss, the temperature of the panels’ surfaces, and the efficiency of the used inverter. Preliminary results showed a strong correlation between sunlight irradiance and ambient temperature with the power generated by solar panels. Thus, these two parameters are chosen as the major inputs to the model. While, the electrical output power and the accumulative energy are set as the output of the simulated model. The study investigates the performance of the proposed model at the hottest day and coldest day throughout the year 2022. The results proved that the system generates more energy during the summer than in the winter due to the strength and a long period of the radiation falling on the ground during this season. Moreover, the investigation study evidenced that the system efficiency decreases as ambient temperatures increase. As the results, the cumulative energy during one day decreased by around 41.366% from the summer to winter. Finally, the authors recommend installing the suggested solar cell system in Iraq because its effectiveness was theoretically proved.

Modeling the Effect of Green Roofs for Building Energy Savings and Air Pollution Reduction in Shanghai

Building energy consumption is an essential source of greenhouse gas (GHG) and air pollution. Green roofs can directly absorb ambient CO2 and remove air pollutants through their vegetation layers, but a limited number of studies have examined their effects on GHG and air pollutant reduction associated with building energy savings, especially in the context of climate change. This research examined the performance of green roofs on CO2 and air pollutant reduction, including SO2, PM2.5, and NOx, through building energy demand savings in Shanghai, China. Climate change mitigation effects were assessed based on the energy consumption of five types of buildings before and after the installation of green roofs under 2020 and 2050 climate conditions, respectively. EnergyPlus software 9.5.0 was applied to simulate hourly energy consumption for different building prototypes with and without green roofs. Green roofs on all building types exhibited positive energy savings on annual, monthly, and diurnal scales, and they can save more energy for most of the building types under the projected 2050 climate condition. Moreover, most of the building energy saved by green roofs came from the Heating, Ventilation, and Cooling (HVAC) systems. In addition, this study discovered that the energy-saving benefits of green roofs vary based on the type of building they were installed on. Green roofs were found to have the largest energy saving on the shopping mall, especially on extremely hot summer days. Finally, a Geographic Information System (GIS)-based approach was developed with the ability to quantify the amount of GHG and air pollutant reduction associated with building energy savings for existing buildings in the Huangpu District of Shanghai. This approach was also utilized to present the spatial distribution of buildings with different levels of suitability to install green roofs by considering their location attributes and air pollutant reduction potential together, which is the major innovation of this research. The purpose of this study is to provide valuable guidance to policy makers regarding the performance of green roofs in building energy-saving and air quality improvement in the urban environment when facing the challenge of climate change, which is essential for urban sustainability.

Temperature Control Strategy to Mitigate Electrical Energy Cost for Air Conditioning

The purpose of this paper is to developed an innovative strategy to support small consumer on reducing the electrical energy cost (EEC), define total electrical energy cost (TEEC) and compute the benefit of the pre-cooling model (BPM). The suggested method enables small consumers to manage the peak electricity demand for air conditioning (AC) autonomously and proactively. In this research, a pre-cooling model (PM) has been applied to anticipate an unexpected level of the electricity price. The main contribution of this research is to develop a PM to avoid an extreme electricity price and examines the EEC, TEEC and compute the BPM during hot days, peak season and considering to the probability spike (Pr). The finding results of research illustrated that the EEC for AC can be reduced from IDR 7539 to IDR 5199 and from IDR 13310 to IDR 9394 for hot days and peak season cases, respectively. The TEEC can be examines to be IDR 5200 and IDR 8888 when the Pr may occur during hot days and peak season, respectively. When applied the proposed method that the consumer and aggregator can earn collective benefit, such as: IDR 2340 (31.03 %) and IDR 3916 (29.42 %) if considering to hot days and peak season respectively; as well as IDR 2159 (28.63 %) and IDR 4422 (33.22 %) if considering to Pr that may occur in the midday and peak season, respectively. Consequently, it can be concluded that the suggested model is effective way to keep comfortable of room temperature, controlling electricity peak demand and reduce electricity cost for the AC. This model is evaluated based on the data from the South Sulawesi electricity market price and demand curves provided by the Indonesian State Electricity Company (referred to as PLN), as well as the value of outside temperature (Tout) considering to characteristic of building in the Makassar region.

The Spatiotemporal Variation Characteristics and Impacts of Summer Heatwaves, Droughts, and Compound Drought and Heatwave Events in Jiangsu Province, China

This study used the “Daily meteorological dataset of basic meteorological elements of China National Surface Weather Station (V3.0)” and applied the absolute threshold method and standardized precipitation evapotranspiration index to identify heatwave events and drought events. This study analyzed the spatiotemporal evolution patterns of three types of summer disaster events, namely, heatwave events, drought events, and compound drought and heatwave events, in Jiangsu Province from 1960 to 2018. Additionally, it investigated and verified the concurrent historical data of the identified years with the most severe occurrence of compound drought and heatwave events and calculated the monthly drought centers and summer accumulations of the standardized precipitation evapotranspiration index (SPEI-3). The results indicate that over the 59 years analyzed, the number of days with a threshold of 35 °C, which were considered hot days, was 503.2, accounting for 9.27% of the total summer days in Jiangsu Province. Both the number of hot days and the frequency of heatwave events showed a clear increasing trend from the northeastern coastal areas to the southwestern regions of Jiangsu Province. The total frequency of drought events at different stations in Jiangsu Province from 1960 to 2018 fell within the range of 50–64. The fitted slope of the frequency of compound drought and heatwave events in Jiangsu Province was −0.021 for the period 1960 to 1989, and 0.079 for the period 1990 to 2018, indicating a higher frequency compared with the preceding 30 years. This trend aligned with the rise in heatwave events experienced in Jiangsu Province in recent years. The frequency and duration of compound drought and heatwave events in Jiangsu Province exhibited an increasing spatial pattern from the southwestern parts to the northeastern parts. This study’s verification established that the identification of compound drought and heatwave events was relatively accurate.

Thermal stress and financial distress: Extreme temperatures and firms’ loan defaults in Mexico

The frequency and intensity of extreme temperature events are likely to increase with climate change. Using a detailed dataset containing information on the universe of loans extended by commercial banks to private firms in Mexico, we examine the relationship between extreme temperatures and credit performance. We find that unusually hot days increase delinquency rates, primarily affecting the agricultural sector, but also non-agricultural industries that rely heavily on local demand. Our results are consistent with general equilibrium effects originated in agriculture that expand to other sectors in agricultural regions. Additionally, following a temperature shock, affected firms face increased challenges in accessing credit, pay higher interest rates, and provide more collateral, indicating a tightening of credit during financial distress.

Plasmochromic Modules for Smart Windows

Active glazing components, which can dynamically regulate incoming solar radiation, are particularly interesting, as they simultaneously impact multiple aspects, such as thermal and visual comfort and overall energy consumption. Near-infrared EC windows (also referred to as “plasmochromic”) enable selective spectral control of the incoming solar radiation and efficiently respond to ever-changing lighting, heating and cooling requirements. They allow to selectively filter a large amount of near-infrared solar radiation passing through the window, thus blocking solar heat gain during hot summer days and letting it permeate over sunny winter days whilst independently regulating the amount of daylight. This article delves into the core attributes of such glazing systems, showcasing recent advancements in their design and fabrication. By evaluating key metrics like luminous transmittance (TLUM), solar transmittance (TSOL), and total solar heat gain coefficient (g-value), the paper presents a preliminary performance assessment of smart glazing employing this technology. Furthermore, the authors prospect the importance of implementing appropriate control strategies for these systems to fully exploit their potential in reducing energy consumption while maximising comfort.

Official heat warnings miss situations with a detectable societal heat response in European countries

The frequency and intensity of heat waves are increasing globally. In this context it is not clear how the related impacts differ between countries with different vulnerability and exposure characteristics, such as overall climatic conditions and implemented adaptation strategies, e.g. urban planning and planting trees to reduce heat island effect, air conditioning, communication with the public about danger of heat waves. The release of official heat warnings two to six days in advance plays an important role in notifying the population. However, it remains uncertain to which extent they capture days with societal heat responses. Here, we analyze and compare the response of several societal metrics (Google search attention, excess mortality, press attention) to hot temperatures in twelve European countries. We identify country-specific temperature thresholds above which societal responses increase. We find higher thresholds in warmer countries, indicating overall lower heat vulnerability in southern Europe. Meanwhile, we find similar numbers of societally relevant hot days across countries, computed as the sum of days on which more than 50 % of a country's population experiencing temperatures above the detected thresholds. This indicates that the reduced vulnerability and exposure found for warmer countries are counteracted by hotter heat waves. Finally, the determined number of societally relevant hot days generally exceeds the number of days with heat warnings in five investigated countries: Belgium, Germany, Netherlands, Romania, and Sweden. This suggests that lower temperature thresholds would be better aligned with detectable societal responses and should therefore be considered in the context of warning systems.

Changes in Temperature and Precipitation Trends in Selected Polish Cities Based on the Results of Regional EURO-CORDEX Climate Models in the 2030–2050 Horizon

This study presents the potential impacts of climate change in 49 Polish cities by analyzing seven climate indicators. The analysis was carried out for the following three horizons: the current climate conditions (an average period spanning 2006 to 2015), near-future conditions (an average period spanning 2026 to 2035), and future conditions (an average period spanning 2046 to 2055). Climate indices were computed with bias-corrected EURO-CORDEX model ensembles from two Representative Concentration Pathway scenarios, RCP4.5 and RCP8.5. The systematic error was reduced using the quantile mapping method with a non-parametric approach of robust empirical quantiles (RQUANT). Data were used as references in the period of current climate conditions, and those required for bias correction consisted of historical ground-based observations provided by the Institute of Meteorology and Water Management. The analysis encompassed various key climate indices, including the annual average temperature, the count of hot days, cold days, and frost days, the cumulative annual precipitation, the frequency of days with precipitation, and instances of extreme precipitation (defined as the days with precipitation exceeding 10 mm/day). These findings reveal a noteworthy rise in the average annual temperature of approximately 1 °C and an uptick in the number of hot days by 3.7 days. Conversely, a decline in the number of cold days by approximately 19 days and frost days by 8 days was observed. Additionally, there was an augmentation in the annual precipitation sum, reaching up to 80 mm in RCP 8.5, accompanied by an increase in the number of days with precipitation (up by 3.3 days) and days with extreme precipitation (up by 2 days).

Drowning incidents in urban rivers: An underestimated issue with future challenges in need of an interdisciplinary database to characterise its epidemiology

In recent decades, the recreational use of urban rivers has become popular, and public access to riverbanks has improved. However, in the context of global warming, the risk of drowning in urban rivers may increase. The objective of this study is to examine drownings in the Rhone and Saone rivers in Lyon (France) and to identify risk factors, hot spots and high-risk moments using an environmental database.A total of 386 fatal and non-fatal drownings occurred in Lyon on the Rhone and Saone rivers between 2015 and 2021. The analyses identify that, universally, most drowning victims are men (68 %) and young adults (37 %). More drownings occur in the summer period (45 %). There are also hot spots near the city centre and in urban river parks. Three types of drownings are characterised by using principal component analysis (PCA) and hierarchical clustering on principal components (HCPC) methods. These groups are distinguished by hydrological and meteorological conditions, as well as by the seasonality and circumstances of the incident. The first group (G1) corresponds to drownings that occur on cold winter days, with high water flows and turbidity. The second group (G2) corresponds to drownings that resulted from bridge jumping in a festive context or a challenge between friends. These drownings occur on autumn days with interesting hydrological conditions (low flow and clear water). The last group (G3) groups together drownings that occurred while a victim is swimming in an unsupervised area. These drownings occur during the summer on very hot days. Finally, a multiple logistic regression method showed that the average daily outdoor temperature was positively correlated with the occurrence of drowning in Lyon (p < 0.05) and that daily rainfall was negatively correlated with the occurrence of drowning (p < 0.05).

Performance analysis of electrical environmental control and ice protection systems in a commercial transport aircraft

PurposeThis paper aims to assess the impact of electrifying the environmental control system (ECS) and ice protection system (IPS), the primary pneumatic system consumers in a conventional commercial transport aircraft, on aircraft weight, range, and fuel consumption.Design/methodology/approachThe case study was carried out on Airbus A321-200 aircraft. Design, modelling and analysis processes were carried out on Pacelab SysArc software. Conventional and electrical ECS and IPS architectures were modelled and analysed considering different temperature profiles.FindingsThe simulation results have shown that the aircraft model with ±270 VDC ECS and IPS architecture is lighter, has a more extended range and has less relative fuel consumption. In addition, the simulation results showed that the maximum range and relative fuel economy of all three aircraft models increased slightly as the temperature increased.Practical implicationsConsidering the findings in this paper, it is seen that the electrification of the conventional pneumatic system in aircraft has positive contributions in terms of weight, power consumption and fuel consumption.Social implicationsThe positive contributions in terms of weight, power consumption and fuel consumption in aircraft will be direct environmental and economic contributions.Originality/valueApart from the conventional ECS and IPS of the aircraft, two electrical architectures, 230 VAC and ±270 VDC, were modelled and analysed. To see the effects of the three models created in different temperature profiles, analyses were done for cold day, ISA standard day and hot day temperature profiles.

Natural ventilation effectiveness in low-income housing to challenge energy poverty

The steady rise in global average temperatures due to climate change is leading to a significant increase in cooling energy demand worldwide. Despite having the least access to energy, the Global South will experience the greatest increase in cooling degree days (CDD), forcing the majority of the world’s population to endure highly uncomfortable temperatures in the buildings. As a result, it becomes crucial to prioritize passive design-based approaches to air conditioning, to mitigate the increasing demand for active cooling while ensuring equitable space cooling opportunities for all. This work, combing the CFD simulation with building energy modeling, evaluates the impact of natural cross-ventilation and building form on improving indoor thermal conditions in hot and arid climates. The analysis, focusing on low-income housing prototypes designed by Indian architect Charles Correa, demonstrates how proper building form design, by improving the ventilation and cooling efficiency of buildings, can ensure indoor thermal comfort even in challenging climatic conditions, helping to reduce energy consumption and prevent energy poverty. Natural ventilation provides an operative temperature reduction of up to 3.1 °C on the hottest day and up to 3.9 °C on the typical cooling period day. Even discomfort hours are drastically reduced by 31.3 % and 77.8 % respectively.

The effects of 2-D and 3-D urban landscape metrics on mean radiant temperature in hot-arid Phoenix and Tempe, Arizona, USA

The composition and configuration of the built environment affect intra-urban heat variability and human thermal exposure. We investigated how 2-D and 3-D building and vegetation characteristics, represented by various landscape metrics, affect the mean radiant temperature (MRT) distribution in Phoenix and Tempe, Arizona, USA, to determine which urban form characteristics are most important for minimizing thermal exposure. For a hot-dry summer day with low wind speed and a maximum air temperature of 43.3 °C, the relationship between 1-m resolution MRT data and seventeen 2-D and 3-D landscape metrics were analyzed at the Census block (micro) and urban (macro) scale. The landscape metrics were calculated with FragStat from a Digital Surface Model, a 3-D point cloud obtained from high-resolution (0.5-m) USGS LiDAR data, and a 1-m resolution land use/land cover map classified from the 2015 National Agriculture Imagery Program (NAIP) data. Hourly MRT for June 27, 2012, was simulated using the SOlar LongWave Environmental Irradiance Geometry (SOLWEIG) model. After testing for autocorrelation in hourly MRT using Moran's I, the relationship between landscape metrics and MRT outcomes was analyzed using correlation coefficients and multiple linear regression. The best predictive power was achieved using 2-D and 3-D metrics together, with an explanation MRT of 86 % (8:00 h) to 96 % (12:00 h). The five most important factors were 3-D vegetation height, 2-D percent tree surface cover, 3-D building height, 2-D building edge density, and the 3-D vegetation height coefficient of variation. Results show that MRT is driven by the composition and configuration of 2-D and 3-D urban features. The horizontal arrangement impacts MRT through varying land cover, and the vertical extent influences shade patterns, with more complex urban forms providing more shade and lowering MRT. Findings advance our understanding of how urban design can reduce thermal exposure on hot days using passive cooling strategies that rely on changes in the configuration and composition of landscapes.

Greening vegetation cools mean and extreme near-surface air temperature in China

Satellite observations have shown evident vegetation greening in China during the last two decades. The biophysical effects of vegetation changes on near-surface air temperature (SAT) remain elusive because prior studies focused on the effects on land surface temperature (LST). SAT is more relevant to climate mitigation and adaptation, as this temperature is experienced by humans. Here, we provide the first observational evidence of the greening effects on SAT and SAT extremes in China during 2001–2018 using the ‘space-for-time’ method. The results show a negative SAT sensitivity to greening (–0.35 °C m2 m–2) over China and a cooling effect of −0.08 °C on SAT driven by vegetation greening during the study period. Such a cooling effect is stronger on high SAT extremes, particularly over arid/semiarid areas, where greening could bring an additional cooling of −0.04 °C on the hottest days. An attribution analysis suggests that the main driving factor for the cooling effect of greening is the evapotranspiration change for arid/semiarid regions and the aerodynamic resistance change for humid regions. This study reveals a considerable climate benefit of greening on SAT, which is more concerned with natural and human system health than the greening effects on LST.

Performance of high-concentration photovoltaic cells cooled by a hybrid microchannel heat sink

The electrical performance and equipment lifetime of high-concentration photovoltaic cells depends heavily on efficient cooling. In this paper, we applied a hybrid configuration to the cooling of a high-concentration photovoltaic cell, an innovative pattern derived from a comprehensive study on the combination of oblique microchannel and micro pin fin. Results from this study found that an elliptical pin fin pattern conforming with streamlines most effectively removed heat flux with a Nusselt number of 65.44 at a Reynolds number 1250. Then, the performance evaluation of a photovoltaic cell with a concentration ratio of 1000 was carried out on the hottest day of each season in Shiraz under actual boundary conditions. With an average flow rate of 30 ml/min in the spring, the implementation of this hybrid design resulted in the photovoltaic cell achieving an electrical efficiency of 40.16 while still maintaining a constant surface temperature of 301 K. Unlike a straight microchannel, which failed to maintain a constant cell temperature throughout summer’s hottest hours, this hybrid configuration succeeded in sustaining cooling with an average flow rate of 90 ml/min. In the winter and autumn, the pump’s average power consumption required for cooling was about 25 and 38 mW, respectively. Moreover, the maximum output electrical power in the summer was 2.8 W, with pumping power contributing to 1500 mW.

Comparison of the Fleece Production of two Extensive French Sheep Genotypes

Sheep fleece became problematic Europe-wide for many reasons, including its very low price. From an animal welfare standpoint, the thick fleece may cause discomfort for the sheep as it can be a welcoming environment for parasites and may cause heat stress during hot summer days; therefore, annual shearing is necessary for most sheep genotypes. Physiologically, growing fleece and maintaining normal body temperature to decrease heat stress distract resources from producing valuable products such as meat. Thus, we aimed to compare the fleece production of two meat-type sheep genotypes from South-France, Berrichon du Cher (Berrichon) and Blanc du Massif Central (BMC), which have relatively little fleece production but thrive in the local Hungarian weather. Furthermore, we fill the gap by providing data on the fleece production of meat-type sheep in Hungary. A total of 180 sheep ewes were included in the data collection (N=99 Berrichon and N=81 BMC). Data was collected at the annual shearing by a digital scale measuring the weight of fleece originating from the back and shoulders. Student’s t test determined the differences in fleece weight between genotypes. Significance was set at P&lt;0.05. The average fleece production of BMC ewes was 1.66 kg, which was significantly (P=0.0001) less than that of Berrichon ewes (2.14 kg). Based on the results, further study is needed to study the performance of BMC ewes with little fleece and their lambs’ in order to improve performance indices and increase profit.