Direct Solar Radiation Research Articles

Evaluation of photocatalytic activity of Cu3(PO4)2/MgO nanocomposite for the efficient removal of amaranth dye under solar light irradiation

The amaranth dye was removed using photocatalysis on a Cu3(PO4)2/MgO nanocomposite synthesized by co-precipitation method. The crystalline component and the nanostructure of the samples were analyzed by XRD, FTIR, UV–vis-DRS, SEM, EDS, HR-TEM and EIS confirming the successful formation of the nanocomposite. In powder XRD, the average crystallite size is found to be ∼ 26–37 nm. Electrochemical impedance spectroscopy, Nyquist plots represents the charge-transfer resistance at contact interface and the arc diameter of Cu3(PO4)2/MgO is much smaller than that of pure MgO and Thermo gravimetric analysis (TGA), from TGA curve the weight-loss of Cu3(PO4)2 and Cu3(PO4)2/MgO nanocomposite was calculated as 14.18 % and 18.16 % which gives the more contribution to the large enhancement of photocatalytic activity. The photocatalytic degradation efficiency of Cu3(PO4)2/MgO nanocomposite (0.1 g/L, 10 μM and 150 min) was investigated under natural direct solar light irradiation against the dyes. The rate of degradation of amaranth with Cu3(PO4)2/MgO followed pseudo–first order kinetics in the dye concentration. Degradation efficiency (99 %) and degradation rates of amaranth were increases with increasing Cu3(PO4)2/MgO concentration. Generally, this research work advances the possible utilization of Cu3(PO4)2/MgO as an efficient catalyst for taking away of dye from aqueous solution and improvement the catalyst to be used for a numerous cycles. The Cu3(PO4)2/MgO nanocomposites showed good activity against bacteria of Staphylococcus aureus, Staphylococcus pyogenes and Klebsilla pneumoniae.

Microclimate Analysis of Outdoor Showcases in Tropical Climate—Two Case Studies in Al Ain, Abu Dhabi, United Arab Emirates

Al Ain, near Abu Dhabi, United Arab Emirates, is characterized by hot desert climate with high temperatures, aridity, and almost no rain. Several truncated earthen walls were discovered at the historic house of Sheikh Mohammed Bin Khalifa, a component of the World Heritage Cultural Sites. These remains are preserved in situ, outdoors, protected in glass showcases for public display. As this situation is not documented in the literature, the local Authority has requested to study the showcase environment to optimize conservation. The solar radiation and the projected shades have been modeled over one year; the temperature and humidity inside and outside the showcases, as well as the moisture content, have been measured to assess the potential preservation risks. The paper presents the results, i.e., the direct solar radiation generates extreme conditions of greenhouse effect with extremely high temperatures and forces evaporation from the remains. During the night, the excess moisture condenses on the inner surface of the glass panes, forming large drops that affect viewing and are dangerous for conservation. The repetition of evaporation–condensation cycles accumulates soluble salts on the remains. The paper discusses mitigation strategies (e.g., shading, ventilation, and cooling, to reduce the greenhouse effect) to improve conservation and fruition.

Design of a Novel Heliostat for a Large-Scale Desalination System

The optical design and the mechanical structure of a new heliostat is described for application in the Solar Water plc large-scale desalination plant, to be constructed in the Middle East. The heliostat field is required to reflect direct solar radiation onto a section of the desalination dome, requiring the design of a new type of heliostat. A novel dual-tilted dual-axis tracking heliostat is the design selected to meet the optical requirements specification. The supporting structure also requires a unique approach, which we describe in this paper. The optical and mechanical analysis of the heliostat and its operation are also presented.

Thermal performance investigation of membrane-assisted radiant cooling system for localised outdoor cooling hub

Heat waves pose increasing threats to human well-being, especially in urban areas, and staying safe beyond comfort during heat waves is a crucial issue. Localised cooling hubs may provide thermal stress relief in the outdoor environment. For outdoor cooling applications, conventional air conditioning systems are not effective but energy-intensive, and the membrane-assisted radiant cooling system can be a potential alternative, which directly treats the radiant loads while minimising the convective heat loss to the ambient. In the present study, a numerical model is developed to analyse the heat transfer behavior of membrane-assisted radiant cooling for outdoor applications, considering the effect of solar and long-wave radiation and wind parameters. As the transmissivity of the membrane material plays a crucial role in reducing the amount of solar heat, the performances of three types of membranes, i.e., non-selective, mid-infrared selective, and sky-window selective, were compared and analysed at different times on a typical summer day in Hong Kong. The results indicate that the sky-window selective membrane, which allows only transmission of infrared in the 8–15 µm wavelength range, saves energy up to 44 % and 47% compared with mid-infrared selective and non-selective membranes, respectively. In the outdoor application, the equivalent convective heat transfer coefficient of the cooling panel can be reduced in the range of 2.2 W/m2K to 2.6 W/m2K. It is observed that, when the panel is not exposed to direct solar radiation, there is no advantage in using the mid-infrared selective membrane over the non-selective membrane. However, under direct solar radiation, a non-selective membrane-assisted cooling panel demonstrates poor performance, absorbing solar heat flux 2.27 times higher compared to MIR-selective membrane-assisted panel.

Evaluating the Influence of Row Orientation and Crown Morphology on Growth of Pinus taeda L. with Drone-Based Airborne Laser Scanning.

The tree crown's directionality of growth may be an indicator of how aggressive the tree is in terms of foraging for light. Airborne drone laser scanning (DLS) has been used to accurately classify individual tree crowns (ITCs) and derive size metrics related to the crown. We compare ITCs among 6 genotypes exhibiting different crown architectures in managed loblolly pine (Pinus taeda L.) in the United States. DLS data are classified into ITC objects, and we present novel methods to calculate ITC shape metrics. Tree stems are located using (a) model-based clustering and (b) weighting cluster-based size. We generated ITC shape metrics using 3-dimensional (3D) alphashapes in 2 DLS acquisitions of the same location, 4 years apart. Crown horizontal distance from the stem was estimated at multiple heights, in addition to calculating 3D volume in specific azimuths. Crown morphologies varied significantly (P < 0.05) spatially, temporally, and among the 6 genotypes. Most genotypes exhibited larger crown volumes facing south (150° to 173°). We found that crown asymmetries were consistent with (a) the direction of solar radiation, (b) the spatial arrangement and proximity of the neighboring crowns, and (c) genotype. Larger crowns were consistent with larger increases in stem volume, but that increases in the southern portions of crown volume were consistent with larger stem volume increases, than in the north. This finding suggests that row orientation could influence stem growth rates in plantations, particularly impacting earlier development. These differences can potentially reduce over time, especially if stands are not thinned in a timely manner once canopy growing space has diminished.

Analysis and determination of the optimal collector array orientation characteristics in solar systems

This paper presents results analysis for the distribution of direct and diffuse solar radiation for a specific climatic zone in Bulgaria. The influence of the slope angle of the collector array over monthly solar radiation incident is studied and regression dependencies regarding incident total, direct and diffuse specific annual solar radiation are derived. Based on the obtained dependencies, the optimal value of the solar collectors slope angle, that guarantees maximum value of the annual solar radiation, is determined. The ratio of direct radiation on an inclined to that on a horizontal surface depending on the azimuth of collector arrays with different slope angle is investigated using a dynamic simulation software. Graphical dependencies, allowing the determination of the total annual solar radiation at different values of the azimuth and the slope angle of the collector array are obtained.

A numerical study of cucurbit cultivation in a greenhouse under direct solar radiation and equipped with a direct evaporative cooler in summer season

The performance of direct evaporative cooler to meet cooling demand of a greenhouse in Tehran in the hottest months of the year as well as water and electricity consumption were numerically studied. The suitable values of air change per hour (ACH) was also obtained for cultivation of tomato, cucumber, eggplant and bell peppers. The k-Ԑ Realizable Turbulence and Discrete Ordinates (DO) models was used for simulating the airflow and estimating radiative heat transfer, respectively. The results showed that an ACH of 10 is proper for tomato cultivation. When the ambient temperature is maximal, an ACH of 15 can be used for cucumber cultivation. However, ACH cannot be kept constant, and ACHs of ≤10 should be utilized when the ambient temperature decreases. For eggplants, it is better to use an ACH 20 at hot hours and an ACH of 10 when the temperature declines. For the bell pepper plant, 20 and 10 ACHs are suitable for day and night hours, respectively. Moreover, the maximum daily water consumed in the greenhouse happens in August and equals 222 lit/day for 20 Air Changes per Hour (ACH). The minimum daily water is consumed in July, equaling 106 lit/day for an ACH of 10. In the present study, the electricity rate consumed in the greenhouse equals 127W when ACH = 20, i.e., the consumed electric energy is 3 kWh for the entire system in a 24-h interval.

A State-of-the-Art Review of Hydronic Asphalt Solar Collector Technology for Solar Energy Harvesting on Road Pavement

Nature inspires innovative renewable energy solutions by advancing our road pavements, as the sun is the only infinite and accessible source of clean and green energy on our planet. In addition to the various solar energy production methods, a new paradigm for utilizing asphalt pavement as a solar collector is being developed for self-powered energy harvesting. Due to direct solar radiation, flexible paved surfaces exposed to direct sunlight can heat up to 70°C in the summer. The heat is then dissipated into the environment, causing the urban heat island effect, and accelerating thermal oxidation of asphalt pavement. This can lead to structural failure and reduced pavement performance. This study aims to present a state-of-the-art review of hydronic asphalt solar collectors (HASCs) and propose the best model to enhance the performance of asphalt solar collectors. The findings of the study concluded that asphalt has the potential to absorb solar energy and store heat energy. This can be achieved by assembling and modifying conventional asphalt structures into modern asphalt solar collector designs that consist of pipe arrangements below the paved surface filled with liquid flowing through the pavement surface. The study found that a significant limitation of previous research was that it focused on optimizing the temperature profile at various depths but did not focus on structural improvements to reduce failure and increase the performance of asphalt solar collectors. Therefore, this review study proposed a new technique of using conductive and waste materials to enhance the performance of asphalt solar collectors.

Detection of Sub-surface Delamination and Moisture Penetration in Unlined Rock Tunnels Using Passive Thermography and Tapping

An unlined rock-blast tunnel constructed by the drill and blast method is susceptible to frequent deterioration, including sagging beds, water ingress and loose rock masses. Thus, assessing potential damages above the roadway that may impact the safety of tunnel users is of utmost importance. While tapping, a conventional nondestructive method, is typically used to predict sub-surface delamination, water ingress can be identified with the naked eye. In this research, we utilized a modern-technology approach called passive thermography, together with a high-resolution digital camera and tapping. The study encountered two primary challenges; namely, the absence of direct solar radiation during the inspection and the groove-exposed surface of the unlined tunnel. The results demonstrated that passive thermography was able to detect delaminated areas and water infiltration on the tunnel's walls and ceiling, even without direct sunlight. Large delaminated areas can be detected with just a 2°C change in atmospheric temperature twelve hours before testing. Additionally, the results of image post-processing significantly contributed to enhancing the results of passive thermography. The thermal image was processed into a grayscale image prior to HE processing, which enhances contrast by over 50%. The combination of tapping, digital camera and passive thermography was proven to be effective in periodically inspecting unlined rock tunnels, while significantly reducing time and cost. KEYWORDS: Tunnel safety, Passive thermography, Old rock-cut tunnel, Hammer sounding, Non-destructive evaluation, Image post-processing.

Global reductions in manual agricultural work capacity due to climate change.

Manual outdoor work is essential in many agricultural systems. Climate change will make such work more stressful in many regions due to heat exposure. The physical work capacity metric (PWC) is a physiologically based approach that estimates an individual's work capacity relative to an environment without any heat stress. We computed PWC under recent past and potential future climate conditions. Daily values were computed from five earth system models for three emission scenarios (SSP1-2.6, SSP3-7.0, and SSP5-8.5) and three time periods: 1991-2010 (recent past), 2041-2060 (mid-century) and 2081-2100 (end-century). Average daily PWC values were aggregated for the entire year, the growing season, and the warmest 90-day period of the year. Under recent past climate conditions, the growing season PWC was below 0.86 (86% of full work capacity) on half the current global cropland. With end-century/SSP5-8.5 thermal conditions this value was reduced to 0.7, with most affected crop-growing regions in Southeast and South Asia, West and Central Africa, and northern South America. Average growing season PWC could falls below 0.4 in some important food production regions such as the Indo-Gangetic plains in Pakistan and India. End-century PWC reductions were substantially greater than mid-century reductions. This paper assesses two potential adaptions-reducing direct solar radiation impacts with shade or working at night and reducing the need for hard physical labor with increased mechanization. Removing the effect of direct solar radiation impacts improved PWC values by 0.05 to 0.10 in the hottest periods and regions. Adding mechanization to increase horsepower (HP) per hectare to levels similar to those in some higher income countries would require a 22% increase in global HP availability with Sub-Saharan Africa needing the most. There may be scope for shifting to less labor-intensive crops or those with labor peaks in cooler periods or shift work to early morning.

Impact of Meteorological Parameters on Solar Radiation over Langtang National Park, Nepal

The main objective of this research is to study the impact of meteorological parameters on atmospheric turbidity index on Langtang National Park (28.2112° N, 85.5663° E, 3862 m asl) for a period of one year (2018). Daily data of Aerosol optical depth (AOD) and meteorological parameters are obtained from AERONET and NASA website respectively. The maximum and minimum values of direct solar radiation (IB) during the study period are found 1286 ± 24 W/m2 in January and 1123 ± 3 W/m2 in August respectively. The maximum and minimum value of diffuse solar radiation (ID) is found 119 ± 21 W/m2 in April and 59 ± 2 W/m2 in August respectively. The annual average of direct solar radiation and diffuse solar radiation are found 1202 ± 63 W/m2 and 90 ± 20 W/m2 respectively. There is a negative effect of maximum temperature, minimum temperature, dew point, relative humidity, water contend and rainfall on IB, but no significant effect of those parameters on ID. The result of this research work is beneficial for the further identification, impact and analysis of solar radiation at different places with same geographical and meteorological condition. The study of solar radiation is important for energy harvesting and agriculture.

Light-thermal environment of vertical translucent enclosure structures under solar radiation and method of internal shading adjustment

Building energy consumption accounts for about one-third of global energy consumption, primarily air-conditioning and lighting. The indoor light-thermal environment is closely related to building energy consumption, and internal shading is an effective adjustment method. To understand the method of adjusting indoor light-thermal environment and energy consumption by internal shading and its adjusting effect, this paper establishes the theory of indoor light-thermal environment as well as the simulation and analysis method. A process for analyzing the light-thermal environment of a room with internal shading was established by calculating and fitting the direct solar radiation, scattered radiation, and indoor daylight illuminance. Secondly, with the goal of building energy saving, the “Internal Shading Light-Thermal Ratio” evaluation method is proposed to evaluate the adjustment effect of curtains. The results of the study show that the building energy consumption saved in the room exhibits a sequentially increasing tendency when the surface reflectivity of the curtains is from 10 % to 100 %, respectively. Thin and thick curtains positively contribute to the light-thermal environment improvement by reducing the office's daylight illuminance by about 58.5 % and 90.8 %, respectively, and the indoor solar heat gain by about 42 % and 79.9 %. Meanwhile, the thin curtains had the best adjustment effect at 17:00. In contrast, the rooms with thick curtains had the best adjustment effect at 18:00. In addition, thin curtains meet the requirements for comfort in a light-thermal environment and are more energy-efficient than the room with thick curtains. Compared to the office without curtains, the building energy consumption of the office with thin curtains decreased by 538 Wh, while the office with thick curtains increased by 357 Wh.

Exploring the comparison of optical, dielectric and photocatalytic performance of Yb3+ and Gd3+ half-doped DyCrO3 nanostructures

The auto combustion sol-gel method was utilized to prepare Dy0.5Gd0.5CrO3 (DGCO) and Dy0.5Yb0.5CrO3 (DYCO) nanomaterials. The single-phase formation of materials was confirmed with the X-ray diffraction technique. Utilizing Kubelka-Munk function, the optical bandgap energy values were found to be 3.39 eV (DGCO) and 2.61 eV (DYCO). The dielectric properties were analyzed in frequency range from 10 kHz to 2 MHz and a temperature range from 25 °C to 225 °C. The conduction mechanism followed the universal Jonscher's power law, which revealed that conduction process was primarily governed by the small polaron hopping. The CBH, NSPT, and QMT models were applicable for the a.c. conduction in the DGCO nanomaterial whereas the CBH and NSPT models were more appropriate for the DYCO nanomaterial. The Kohlrausch, Williams and Watts function was used to correlate the imaginary electrical modulus spectrum, which confirmed that the relaxation process in the materials was non Debye-type. An impedance spectroscopic measurement revealed the influence of grain and grain boundaries and it followed negative temperature coefficient resistance behaviour at higher temperatures. Both DGCO and DYCO nanomaterials were also investigated for their photocatalytic degradation of Rhodamine B (RhB) and Methylene Blue (MB) dyes. The degradation, under direct solar irradiation, was 84 % (RhB) and 63 % (MB) for DYCO nanomaterial and 54 % (RhB) and 44 % (MB) for DGCO nanomaterial, indicating their potential in water treatment.

FLAP Heliostat

Heliostats represent a major cost share of concentrating solar power (CSP) plants with central receiver. They are essential for system efficiency and strongly influence maintenance cost and service life. Since CSP facilities require direct solar radiation, suitable installation sites can eminently be found in desert regions. However, dusty conditions may greatly reduce the performance of the plant due to soiling of the heliostat’s reflective surface and / or irreversible degradation caused by abrasive sand particles. A novel heliostat called FLAP, developed specifically for desert environments, is presented in this paper. It was designed with an emphasis on maximum manufacturing and maintenance cost reduction, yet improved service life in mind. The essential innovation of the FLAP heliostat is the patented foldable reflector support structure consisting of two panel sections that are oriented face-to-face when being in lay-down stow position. Folding of the panels is accomplished by means of a mechanism comprising a simple yet effective 4-bar linkage. To avoid costs for additional drives, the device is actuated by the one single central linear actuator that is also used for elevation tracking. Furthermore, wind loads are minimized due to the low profile of the heliostat structure in stow position, resulting in material and hence overall cost savings.

Effects of the clothing colors on heat transfer and thermal sensation under indoor solar radiation in winter

The clothing color could always produce different human heat transfer and thermal sensation under solar radiation. And this issue has already been scrutinized by a few studies in outdoor environment. As the natural lighting is becoming common in buildings, e.g. the large curtain walls in high-rise buildings, the direct solar radiation could also affect the indoor occupants. Consequently, effects of the clothing color on the human body could not be ignored. Unfortunately, very limited studies have been reported in this field. In order to acquire the contribution of the clothing color to the heat transfer and thermal sensation of the indoor occupants, experimental study was conducted in this paper. Firstly, considering the non-uniformity of direct solar radiation on the indoor occupants, the equations that were used to calculate the solar heat gain of different body segments and the clothing surface temperature were revised, respectively. Thereafter, an experimental study was conducted in a climate chamber in winter. Participants wore cloth with different colors when exposed to different solar radiation intensities, during which the mean skin temperature, heat transfer, and subjective evaluations were acquired. Results showed that the dark clothing led to the reduced total heat loss by 4.52%, compared with that of the light clothing, at the solar radiation intensity of 200 W/m2. And the mean thermal sensation vote (TSV) under dark clothing was 0.65 higher than that under the light clothing. Meanwhile, at the solar radiation of 400 W/m2, the total heat loss under dark clothing was 14.17% lower than that under the light clothing, and the mean TSV under the dark clothing was found to be 0.25 higher that under light clothing condition. The results implied that wearing the dark clothing could benefit the improvement of the indoor human thermal comfort at low solar radiation in winter. These findings could provide a few useful references for studies on indoor thermal comfort under the solar radiation.

Minimum entropy production in inhomogeneous thermoelectric materials

Due to their potential applications in energy production based on waste heat, direct solar radiation or other energy sources, semiconductor materials have for years attracted the attention of theoretical and experimental researchers. The focus has been on improving the performance of thermoelectric devices through several strategies and special interest has been placed on materials with spatially inhomogeneous transport properties. Inhomogeneity can be achieved in various ways, all of them leading, to a greater or lesser extent, to an improvement of the thermoelectric performance. In this paper, general linear heat and electric charge transport processes in inhomogeneous materials are addressed. The guiding idea followed here is that there exists a relationship between inhomogeneity (structuring), minimum entropy production and performance which may be fruitfully exploited for designing more efficient thermoelectric semiconductor devices. We first show that the stationary states of such materials are minimum global entropy production states. This constitutes an extension of the validity of Prigogine’s minimum entropy principle. The heat and charge transport equations obtained within the framework of classical irreversible thermodynamics are solved to find the stationary profiles of temperature and self-consistent electric potential in a one-dimensional model of a silicon–germanium alloy subjected to an external temperature difference. This allows us to assess the effect of the spatial inhomogeneity on the thermoelectric performance. We find that, regardless of the value of the applied temperature difference, the system may efficiently operate in a regime of minimum entropy production and high efficiency.

Retrieval of NO2 Tropospheric Column from Ground-Based FTIR Measurements of Direct Solar Radiation

Retrieval of NO2 Tropospheric Column from Ground-Based FTIR Measurements of Direct Solar Radiation

Daylight performance of the Modified Double Light Pipe (MDLP) through yearly experimental tests on a scale model of the system

This work focuses on the Modified Double Light Pipe (MDLP), a daylighting system designed to improve the performance of the Double Light Pipe (DLP).The paper shows the results of a yearly experimental activity carried out on a 1:2 scale model of the device. The dynamic metrics DA, cDA, and U0 have been calculated on a seasonal and yearly basis, and the internal illuminance trend has been determined in four representative days: winter and summer solstices, and spring and autumn equinoxes.The system is effective in delivering daylight in underground areas of buildings both on sunny and cloudy days. Particularly, under overcast sky, a good congruence between internal and external illuminances happens, and linear regression equations allow us to determine the internal illuminance as a function of the external one. Under clear sky with sun, this correlation is less precise at the corners of the room, due to the presence of direct solar radiation, while remaining accurate in the central area. The daylight autonomy is significant for target values of 50 and 100 lx, particularly in spring and summer. DA100 ranges between 0.58 and 0.83 in spring and between 0.66 and 0.83 in summer. The uniformity of daylight distribution on the horizontal work plane can be considered acceptable quite in all climatic conditions, particularly in spring and summer with U0 higher than 0.7 in 81 % (spring) and 85 % (summer) of cases. Altogether, the results can be considered satisfactory.

Mapping subcanopy light regimes in temperate mountain forests from Airborne Laser Scanning, Sentinel-1 and Sentinel-2

Sunlight is the primary source of energy in forest ecosystems and subcanopy light regimes largely determine the establishment, growth and dispersal of plants and thus forest floor plant communities. Subcanopy light regimes are highly variable in both space and time, which makes monitoring them challenging. In this study, we assess the potential of Sentinel-1 and Sentinel-2 time series for predicting subcanopy light regimes in temperate mountain forests. We trained different random forest regression models predicting field-measured total site factor (TSF, proportion of potential direct and diffuse solar radiation reaching the forest floor, here defined as the transition zone between belowground and aboveground biomass) from a set of metrics derived from Sentinel-1 and Sentinel-2 time series. Model performance was benchmarked against a model based on structural metrics derived from Airborne Laser Scanning (ALS) data, serving as an empirical gold-standard in modelling subcanopy light regimes. We found that Sentinel-1 and Sentinel-2 time series performed nearly as good as the model based on high-resolution ALS data (R2/RMSE of 0.80/0.11 for Sentinel-1/2 compared to R2/RMSE of 0.90/0.08 for ALS). We furthermore tested the generalizability of the trained models to two new sites not used for training for which field data was available for validation. Prediction accuracy for the ALS model decreased substantially for the two independent test sites due to variable ALS data quality and acquisition date (ΔR2/ΔRMSE of 0.29/0.05 and 0.11/0.03 for both independent test sites). The prediction accuracy of the Sentinel-1/2 model, however, remained more stable (ΔR2/ΔRMSE of 0.13/0.02 and 0.13/0.04). We therefore conclude that a combination of Sentinel-1 and Sentinel-2 time series has the potential to map subcanopy light conditions spatially and temporally independent of the availability of high-resolution ALS data. This has important implications for the operational monitoring of forest ecosystems across large scales, which is often limited by the challenges related to acquiring airborne datasets.

Cirques in the Transantarctic Mountains reveal controls on glacier formation and landscape evolution

In this study, we analyse the morphometry of cirques in the Transantarctic Mountains (TAM) to understand regional glacier formation and landscape evolution since the onset of Cenozoic glaciations. We find that, unlike most glacierised regions worldwide, aspect bias for cirques in the TAM is not particularly strong, indicating that glaciers were able to form and cirques develop on slopes with a variety of aspects. This is perhaps unsurprising, given that Antarctica's climate has been conducive to long-lived and extensive glaciation for many millions of years. Surprisingly, where cirques in the TAM show an aspect bias, this is typically towards the North, NW and/or NE, rather than favouring South-facing slopes where direct solar radiation is comparatively limited. This lack of a poleward aspect bias is unlike most cirque populations globally and indicates that total solar insolation was not a key control on where former glaciers in the TAM were able to initiate. Instead, we argue that prevailing wind directions played a dominant role in controlling the slopes on which past glacier development was favoured. Specifically, South-facing slopes in the TAM are directly exposed to katabatic winds which originate from the interior of the East Antarctic Ice Sheet (EAIS). These slopes are therefore susceptible to wind deflation, with snow and ice being redistributed to lee-side slopes where it can accumulate due to protection from the wind. For this reason, North, NE and/or NW facing slopes may have favoured glacier development, and therefore resulted in a concentration of cirques with these aspects. This evidence suggests that most cirques in the TAM are no older 34 Ma, as outward radiating winds from the continent's interior could only have prevailed when the EAIS was present (in some form). By contrast, the very highest (and likely oldest) cirques in the TAM have more varied aspects, indicating that they may have formed before katabatic winds came to dominate, and by extension, before widespread growth of the EAIS at 34 Ma, and could perhaps have formed as far back as 60 Ma. In general, we find that cirques in the TAM have similar dimensions to those in other regions globally, despite having been occupied by glacial ice for far longer. Thus, our findings support a growing body of evidence which suggests that cirque size and glacier occupation times are not directly coupled, though there is some evidence of spatial variability in cirque size which might relate to the differences in the dynamics of former glaciers.