Effect Of Solar Heating Research Articles

Study on Simulation for Solar Heating System for Biogas

The anaerobic methane fermentation is sensitive to temperature, the higher the temperature, the more vigorous microbial activity, higher gas production. Therefore, the temperature is the main factor of methane fermentation. Northern regions due to low temperatures, biogas will be difficult to operate on their own, the need for digester heating. Solar heating is a heating system, biogas fermentation method. Effect of solar heating on the methane fermentation is one of the hotspots in this field. Using MATLAB to provide dynamic system modeling and simulation package Simulink, solar heating methane fermentation system model and algorithm, select the appropriate module on the biogas fermentation solar heating simulation, the method for solar heating in north China to provide a methane fermentation system some new ideas.

Primary Beam and Dish Surface Characterization at the Allen Telescope Array by Radio Holography

The Allen Telescope Array (ATA) is a cm-wave interferometer in California, comprising 42 antenna elements with 6-m diameter dishes. We characterize the antenna optical accuracy using two-antenna interferometry and radio holography. The distortion of each telescope relative to the average is small, with RMS differences of 1% of beam peak value. Holography provides images of dish illumination, characterizing as-built mirror surfaces. Maximal distortions across ~ 2 meter lengths appear to result from mounting stresses or solar radiation. Experimental RMS errors are 0.7 mm at night and 3 mm under worst-case solar illumination. For frequencies 4, 10, and 15 GHz, the nighttime values indicate sensitivity losses of 1, 10 and 20%, respectively. ATA's wide-bandwidth receiver permits observations over a continuous range 0.5-11.2 GHz. We probe the antenna optical gain and beam pattern stability as a function of focus position and observation frequency, concluding that ATA can produce high fidelity images over a decade of simultaneous observation frequencies. We quantify solar heating effects on antenna sensitivity and pointing accuracy. We find that during the day, observations >;5 GHz will suffer some sensitivity loss and it may be necessary to make antenna pointing corrections on a 1-2 hourly basis.

Optimum salt-gradient solar pond in Jordan

The salt gradient solar ponds comprise a hydraulic system subject: to processes at heat; and mass transfer. A brief description of the various models of solar ponds, their main objectives and their development, including a detailed review of the world wide activities in this field were given. These models can usually give good indication of seasonal variation in pond performance and effect of varying the design parameter. Mathematical model is performed to a one dimension transient conduction with heat generation salt gradient solar pond SGSP, with incorporation of the attenuation model for the solar radiation through the water body proposed by Brinkworth and Hawalder, with detailed representation of the loss from the pond service and using the daily monthly averaged local available meteorological data for Dead Sea region in the middle of Jordan (31.03° N lat) and (348° E long). The relationship derived are solved numerically by employing an implicit finite difference approach. Numerical results have clearly shown that the solar heating effect appears considerably more pronounced during the hot seasons (spring and summer).

Solar radiative heating of fiber‐optic cables used to monitor temperatures in water

In recent years, applications of distributed temperature sensing (DTS) have increased in number and diversity. Because fiber‐optic cables used for DTS are typically sheathed in dark UV‐resistant materials, the question arises as to how shortwave solar radiation penetrating a water column influences the accuracy of absolute DTS‐derived temperatures in aquatic applications. To quantify these effects, we completed a modeling effort that accounts for the effects of radiation and convection on a submersed cable to predict when solar heating may be important. Results indicate that for cables installed at shallow depths in clear, low‐velocity water bodies, measurable heating of the cable is likely during peak solar radiation. However, at higher velocities, increased turbidity and/or greater depths, the effects of solar heating are immeasurable. A field study illustrated the effects of solar radiation by installing two types of fiber‐optic cable at multiple water depths (from 0.05 to 0.8 m) in the center and along the sidewall of a trapezoidal canal. Thermistors were installed at similar depths and shielded from solar radiation to record absolute water temperatures. During peak radiation, thermistor data showed small temperature differences (∼0.003°C–0.04°C) between depths suggesting minor thermal stratification in the canal center. DTS data from cables at these same depths show differences of 0.01°C–0.17°C. The DTS differences cannot be explained by stratification alone and are likely evidence of additional heating from solar radiation. Sidewall thermistor strings also recorded stratification. However, corresponding DTS data suggested that bed conduction overwhelmed the effects of solar radiation.

Solarization as a method for producing fungal-free container soil and controlling wilt and root-rot diseases on cucumber plants under greenhouse conditions

The effect of solar heating on mulched or un-mulched soil on Fusarium wilt or Rhizoctonia root-rot diseases under greenhouse conditions was studied. Isolation and pathogencity tests proved that the most pathogenic fungi of wilt and root-rot were Fusarium oxysporium f.sp. cucumerinmum (isolate No 2) and R. solani (isolate No. 2), respectively. It caused wilt and root-rot diseases by 26.4, 67.7% and 41.0 and 71.0% at pre- and post-emergence stages of cucumber, respectively. Nylon bags containing soil artificially infested with the inoculum of F. oxysporium f.sp. cucumerinum or Rhizoctoia solani were buried 10–20 cm below the soil surface in either mulched or un-mulched soil for 4, 6, or 8 weeks and were evaluated for mulching effects on reduction of fungal population density and disease incidence. Results indicated that the reduction of fungal population increases as the period of soil mulching was prolonged. The large reduction in F. oxysporium f.sp. cucumerinum and R. solani population (99%) was obtained in soil mulching for eight weeks and decreased gradually to reach its minimum (55%) after four weeks of mulching soil. Cucumber plants were transplanted in pots containing previously buried soil under mulching or un-mulching conditions. The effectiveness of soil solarization on wilt or root-rot incidence of cucumber was evaluated under greenhouse conditions. The highest reduction in Fusarium wilt or Rhizoctonia root-rot was obtained in mulched soil for eight weeks. It reduced the pre- and post-emergence more than 88.5 and 95.2%, respectively, compared with untreated control. On the other hand, un-mulched soil reduced the wilt or root-rot diseases by more than 46.2 and 49.1% for pre- and post-emergence, respectively. The results obtained indicate that the fungus remained active for four weeks in un-mulched soil. It could be suggested that soil-solarization for eight weeks proved highly efficacious for reducing wilt and root-rot pathogens of cucumber plants, and might be considered as applicable treatment for controlling such soil-borne plant pathogens.

The Diurnal Cycle of Winds, Rain, and Clouds over Taiwan during the Mei-Yu, Summer, and Autumn Rainfall Regimes

Abstract The diurnal variations in surface winds, rain, and clouds over Taiwan are presented for three rainfall regimes: the mei-yu (16 May–15 June), summer (16 July–31 August), and autumn (16 September–15 October). Though the magnitude of diurnal island divergence and convergence is similar under each regime, the diurnal variations of rain and clouds vary considerably between the regimes. These differences are related to the seasonal changes in environment winds, stability, moisture, and weather systems. In addition to orographic lifting on the windward side, rainfall occurrences for all three rainfall regimes are strongly modulated by the diurnal heating cycle with an afternoon maximum. The largest day–night differences in rainfall occur in summer and the smallest differences occur in autumn. The upper-level high cloud (<235 K) frequencies have a pronounced afternoon maximum over the mountainous areas in the afternoon because of combined effects of orographic lifting and solar heating. These clouds are advected downstream by the upper-level winds in late afternoon and early evening. The highest afternoon high cloud frequencies occur in summer (>30%) with the lowest upper-level cloud cover in autumn (∼10%). In autumn, most of the orographic showers on the eastern and northeastern windward side in the late afternoon and early evening are not from deep clouds. The weak early-morning rainfall maxima for all three seasons are related to the localized boundary layer convergence due to the orographic blocking of the prevailing winds and their interactions with the offshore/land breeze. During disturbed, prefrontal periods in the mei-yu, bands of high clouds and rain tend to develop in the early morning in the convergence zone off the northwest coast. These rainbands are responsible for the early-morning rainfall maximum on the northwest coast. They do not occur in summer or autumn.

Dynamical effects of solar heating below the cloud layer in a Venus‐like atmosphere

The dynamics of Venus' lower‐atmospheric superrotation remain an open issue. In the present study, we investigate the sensitivity of the superrotation to diabatic heating rate below the cloud layer using a simplified GCM. A fully developed superrotation fails to develop in the lower atmosphere under the condition with a fairly low diabatic heating below the cloud layer, as is thought to be realistic. Additional radiative forcing in the lower atmosphere and/or eddy momentum source should be considered to produce lower‐atmospheric superrotation. The diabatic heating rate below the cloud layer controls the formation of the multiple superrotation states (slow, fast, and extremely fast superrotations). Small changes in the weak lower‐atmospheric heating lead to drastic changes of the middle‐ and lower‐atmospheric superrotation.

Improved multisensor approach to satellite‐retrieved near‐surface specific humidity observations

A multisensor microwave retrieval of near‐surface 10 m specific humidity (Qa) using satellite observations from the advanced microwave sounding unit‐A (AMSU‐A), the Special Sensor Microwave Temperature Sounder‐2, and the Special Sensor Microwave Imager is improved upon in this study. Refinements to the regression formula, training data set, collocation procedure, and height adjustment to 10 m were used to improve retrievals from two different sensor combinations. Independent validation with the International Comprehensive Ocean‐Atmosphere Data Set (ICOADS) indicates a lower overall bias of ∼0.3 g/kg and a smaller root‐mean‐square difference of ∼0.4 g/kg than with several previously published single‐sensor Qa retrievals. A significant regional Qa wet bias of ∼3 g/kg in the summer over the North Pacific was found for all satellite retrievals, and a correction was developed using an inversion index defined using sea surface temperature and AMSU‐A lower tropospheric temperature observations. An assessment of ICOADS ship and buoy validation data indicated uncertainties related to height adjustments of these in situ observations to be 0.2–0.4 g/kg, while hygrometer differences and solar heating effects had smaller uncertainties of less than 0.05 g/kg. Validation of the updated multisensor retrievals with ICOADS over an 8‐year period from 1999 to 2006 revealed a reduced magnitude of the regional biases when compared to previously published retrievals. Regional Qa differences, particularly in the subtropical high regions, are shown to play a significant role in determination of surface latent heat flux.

Sulfur hexafluoride as a complementary method for measuring the extent of point-source thermal effluents

The transport and dilution dynamics of power-plant thermal effluent were measured for 10 consecutive days, between 25 June and 4 July 2006, by concurrently mapping the daily distributions of seawater temperature and concentrations of deliberately released sulfur hexafluoride (SF6) within the tidal Kwangyang Bay on the southern coast of Korea. Estimates of the daily extent of the thermal plume based on temperature and SF6 data showed distinct differences. These differences were particularly pronounced on sunny days during which solar radiation significantly heated river or bay waters moving across the tidal flats; in these cases, the estimates based on seawater temperature data were consistently greater than those based on SF6 data, indicating considerable overestimates of the extent of the thermal plume when temperature data were used. The present results indicate that the concurrent use of seawater temperature and SF6 data is a powerful method in determining the extent of thermal plumes, particularly for shallow areas in which the effects of solar heating lead to large uncertainties in temperature-based estimates.

Cyanide recovery by tailings washing and pond stripping

Modern gold producers are experiencing the operational dichotomy of minimizing wildlife exposure to toxic levels of cyanide in tailings and process waters, while decreasing operating costs for exploitation of lower-grade ores. The widely accepted tailings weak-acid dissociable (WAD) cyanide level of <50 mg/L is typically achieved by oxidation of cyanide using reagents such as SO 2/air, H 2SO 5 or H 2O 2. Consumption rates and costs of these processes can be substantial; moreover, destruction of the reagent that is often the single largest operating cost centre for the process plant represents an additional economic downside. Technical and economic aspects of an alternative process for achieving these eco-efficiency objectives with minimal additional hazardous chemicals are considered and compared against other process alternatives for a selected scenario. The WPS (washing – pond stripping) process comprises tailings slurry washing using counter-current high-rate thickeners and pond or tank stripping of cyanide from the thickener overflow. Water balance issues are avoided by use of cyanide-stripped water along with any make-up water requirements in the washing stage. The cyanide-rich caustic scrub solution is recycled to the leach. Metals and other species that may build up in plant process waters even in the absence of tailings thickening can be treated by a variety of conventional measures. The WPS process is based on proven unit operations and hence utilizes existing plant infrastructure and other resources wherever possible. Single tailings thickeners are used in some gold plants for the recycle of water, along with a portion of the cyanide and soluble gold losses; this equipment can be better utilized by washing with recycle water to raise recoveries to high levels. Moreover, removal of cyanide from the overflow water improves management of the water balance and reduces cyanide consumption in the mill. The existing process water pond or tank is augmented with a covering commonly used in the water treatment industry for biogas production and odour removal. This low-pressure system provides a long retention time for the HCN stripping process, and the positive effect of pond solar heating on the Henry’s Law constant can also improve the thermodynamic driving force for stripping. The covered pond eliminates wildlife deaths in this area of the site; by also venting the carbon-in-leach (CIL) tanks in-circuit cyanide losses are further minimized, resulting in lower lime consumption by operating at lower pH conditions. Scrubbing systems are increasingly being designed in to new and existing gold circuits for the removal of cyanide, ammonia, volatile organic compounds (VOCs) and mercury from carbon regeneration kiln and gold room off-gas streams. Moreover, the occupational health and safety issues regarding elevated HCN levels above leach tanks employing hypersaline waters may require venting and scrubbing systems to be introduced. The additional soluble gold that is recovered in the WPS process can be a significant economic driver along with the advantages of cyanide recovery over destruction. The environmental risk of ongoing cyanide tailings management is minimized, while providing economic benefits from the recovery of cyanide, water and gold.

Spatially distributed temperatures at the base of two mountain snowpacks measured with fiber-optic sensors

AbstractSnowpack base temperatures vary during accumulation and diurnally. Their measurement provides insight into physical, biological and chemical processes occurring at the snow/soil interface. Recent advances in Raman-spectra instruments, which use the scattered light in a standard telecommunications fiber-optic cable to infer absolute temperature along the entire length of the fiber, offer a unique opportunity to obtain basal snow temperatures at resolutions of 1 m, 10 s and 0.1°C. Measurements along a 330 m fiber over 24 hours during late-spring snowmelt at Mammoth Mountain, California, USA, showed basal snow temperatures of 0 ± 0.2°C using 10 s averages. Where the fiber-optic cable traversed bare ground, surface temperatures approached 40°C during midday. The durability of the fiber optic was excellent; no major damage or breaks occurred through the winter of burial. Data from the Dry Creek experimental watershed in Idaho across a small stream valley showed little variability of temperature on the northeast-facing, snow-covered slope, but clearly showed melting patterns and the effects of solar heating on southwest-facing slopes. These proof-of-concept experiments show that the technology enables more detailed spatial and temporal coverage than traditional point measurements of temperature.

Effects of Solar Heating for Control of Pink Root and Other Soil-borne Diseases of Onions

These experiments were carried out to examine efficacy of soil solarization for control of pink root disease by means of mulching with transparent polyethylene sheets in the hot season. The effects of soil solarization on incidence of pink-root disease caused by Pyrenochaeta terrestris and on onion growth and on populations of soil fungi were investigated. Solarization was dramatically effective in reducing pink root incidence in onion seedling and harvested onion bulb. A 30-day and 40-day solarization treatment significantly improved seedling survival and increased yield of 'Changnyeong-deago' onion while decreasing incidence of pink root. Populations of soil fungi from fields planted to onion were assayed on selective media. Solarization treatment was effective in reducing populations of P. terrestris, Pythium spp., and Rhizoctonia sp. in soil. Increase of yield of onion bulbs was associated with control of soil-borne pathogenic fungi. Soil solarization had beneficial effects on yield, bulb diameter, or incidence of pink root.

Thermal surface characteristics of coal fires 1 results of in-situ measurements

Natural underground coal fires are fires in coal seams occurring subsurface. The fires are ignited through a process named spontaneous combustion, which occurs based on a natural reaction but is usually triggered through human interaction. Coal mining activities expose coal to the air. This leads to the exothermal oxidation of the carbon in the coal with the air's oxygen to CO 2 and – under certain circumstances – to spontaneous combustion. Coal fires occur in many countries world wide – however, currently the Chinese coal mining industry faces the biggest problems with coal fires. Coal fires destroy the valuable resource coal and furthermore lead to many environmental degradation phenomena such as the deterioration of surrounding vegetation, land subsidence and the emission of toxic gasses (CO, N 2O). They additionally contribute to the emission of green house relevant gasses such as CO 2 and CH 4 to the atmosphere. In this paper we present thermal characteristics of coal fires as measured in-situ during a field campaign to the Wuda coal fire area in south-central Inner Mongolia, China. Thermal characteristics include temperature anomaly measurements at the surface, spatial surface temperature profiles of fire areas and unaffected background areas, diurnal temperature profiles, and temperature measurements inside of coal fire induced cracks in the overlying bedrock. For all the measurements the effects of uneven solar heating through influences of slope and aspect are considered. Our findings show that coal fires result in strong or subtle thermal surface anomalies. Especially the latter can easily be influenced by heating of the surrounding background material through solar influences. Temperature variation of background rocks with different albedo, slope, aspect or vegetation cover can substantially influence the detectability of thermal anomalies. In the worst case coal fire related thermal anomalies can be completely masked by solar patterns during the daytime. Thus, night-time analysis is the most suitable for thermal anomaly mapping of underground coal fires, although this is not always feasible. The heat of underground coal fires only progresses very slowly through conduction in the rock material. Anomalies of coal fires completely covered by solid unfractured bedrock are very weak and were only measured during the night. The thermal pattern of underground coal fires manifested on the surface during the daytime is thus the pattern of cracks and vents, which occur due to the volume loss underground and which support radiation and convective energy transport of hot gasses. Inside coal fire temperatures can hardly be measured and can only be recorded if the glowing coal is exposed through a wider crack in the overlaying bedrock. Direct coal fire temperatures measured ranged between 233 °C and 854 °C. The results presented can substantially support the planning of thermal mapping campaigns, analyses of coal fire thermal anomalies in remotely sensed data, and can provide initial and boundary conditions for coal fire related numerical modeling. In a second paper named “Thermal Characteristics of Coal Fires 2: results of measurements on simulated coal fires” [ Zhang J., Kuenzer C., Tetzlaff A., Oettl D., Zhukov B., Wagner W., 2007. Thermal Characteristics of Coal Fires 2: Result of measurements on simulated coal fires. Accepted for publication at Journal of Applied Geophysics. doi:10.1016/j.jappgeo.2007.08.003] we report about thermal characteristics of simulated coal fires simulated under simplified conditions. The simulated set up allowed us to measure even more parameters under undisturbed conditions — especially inside fire temperatures. Furthermore we could demonstrate the differences between open surface coal fires and covered underground coal fires. Thermal signals of coal fires in near range thermal remotely sensed imagery from an observing tower and from an airplane are presented and discussed.

Water masses in the Monterey Bay during the summer of 2000

Water masses in Monterey Bay are determined from the CTD casts of the Monterey Ocean Observing System (MOOS) Upper-water-column Science Experiment (MUSE) August 2000 dataset. It is shown through cluster analysis that the MUSE 2000 CTD dataset contains 5 water masses. These five water masses are: bay surface water (BSW), bay warm water (BWW), bay intermediate water (BIW), sub arctic upper water (SUW) and North Pacific deep water (NPDW). The BWW is a new water mass that exists in one area and is attributed to the effects of solar heating. The volumes occupied by each of the water masses are obtained. The BIW water is the most dominant water mass and occupies 68.8% of the volume. The statistical means and standard deviations for each water parameter, including spiciness and oxygen concentration, are calculated during separate upwelling and relaxed periods. The water mass content and structure are analyzed and studied during upwelling and a relaxed period. During upwelling, along a CTD track off Pt. Ano Nuevo, the water mass T, S distribution tended to be organized along three branches. Off Pt. Ano Nuevo the innovative coastal observation network (ICON) model showed the formation of a cyclonic eddy during the analyzed upwelling period. In time the eddy moved southwest and became absorbed into the southerly flow during the initial phases of the following wind-relaxed period.

Metallic Abundances of 2002 Leonid Meteoroids in Two Dust Trails Formed in Different Epochs: No Evidence of Solar Heating Effect

High-definition TV spectra in the ultraviolet to visible region were obtained during the 2002 Leonid aircraft campaign. We analyzed 20 meteor spectra obtained from the 1767 (seven revolution) and 1866 (four revolution) trails on 2002 November 19 and identified neutral atoms, mainly Mg I, Fe I, Ca I, and Na I, in the observed wavelengths between 300 and 650 nm. The singly ionized atomic emissions, Ca II and Mg II lines, also appeared in the spectrum. The abundances of the metallic atoms, the electronic excitation temperature, and the electron density are obtained for each spectrum, assuming the Boltzmann distribution for the number at each energy level. The metallic abundances of Fe, Ca, and Na relative to Mg are slightly lower than solar abundances on average. We could not find any evidence of the solar heating effect on Leonid meteoroids between the 1767 and 1866 trails on orbit with their perihelion (q ~ 1 AU). We can support the idea that silicate and carbon-mixed silicate are preserved in interplanetary space for at least several hundred years. Bands of CHON-related molecules, such as OH and CN, are not detected in this study.

Transient heat and mass transfer and long-term stability of a salt-gradient solar pond

In this work, the problem of transient heat and mass transfer and long-term stability of a SGSP has been numerically investigated using a 2D-transient-variable properties model and a finite-control-volume numerical method. The pond, which was assumed initially stabilized with linear temperature and salinity profiles, has been subject to real weather conditions. The numerical model has been satisfactorily validated against measured temperature data. Numerical results have clearly shown that the solar heating effect appears considerably more pronounced during the hot seasons (spring and summer) than during the cold ones (winter and autumn). The existence of two critical zones, one beneath the water surface and the other one located near the pond bottom, has clearly been established at a very early time of operation. It has been found that such critical zones have progressively become more vulnerable in time. Also, the solar heating effect, the heat losses through the free surface as well as the water transparency have an important influence on the pond stability characteristics and its temporal evolution. The presence of a heat extraction with its cooling effect tends to stabilize the pond. Such a beneficial effect, which is mainly observed in the bottom region of the pond, has been found to be more pronounced during the summer than during the winter time. Results have also shown that the pond with good transparency water would likely be more susceptible to develop instabilities than the one with poorer transparency water. Such an effect appears to be more important inside the lower critical zone.

Infrared Interferometric Measurements of the Near-Surface Air Temperature over the Oceans

Abstract The radiometric measurement of the marine air temperature using a Fourier transform infrared spectroradiometer is described. The measurements are taken by the Marine-Atmospheric Emitted Radiance Interferometer (M-AERI) that has been deployed on many research ships in a wide range of conditions. This approach is inherently more accurate than conventional techniques and can be used to determine some of the error characteristics of the standard measurements. Examples are given from several cruises ranging from the Arctic to the equatorial Pacific Oceans. It is shown that the diurnal heating signal in radiometric air temperatures in the tropical Pacific can typically reach an amplitude of ∼15% of that measured by conventional sensors. Conventional data have long been recognized as being contaminated by direct solar heating and heat island effects of the ships or buoys on which they are mounted, but here this effect is quantified by comparisons with radiometric measurements.

Radiative Impacts on the Growth of Drops within Simulated Marine Stratocumulus. Part I: Maximum Solar Heating

Abstract The effects of solar heating and infrared cooling on the vapor depositional growth of cloud drops, and hence the potential for collection enhancement, is investigated. Large eddy simulation (LES) of marine stratocumulus is used to generate 600 parcel trajectories that follow the mean motions of the cloud. Thermodynamic, dynamic, and radiative cloud properties are stored for each trajectory. An offline trajectory ensemble model (TEM) coupled to a bin microphysical model that includes the influences of radiation on drop growth is driven by the 600-parcel dataset. In line with previous results, including infrared cooling causes a reduction in the time for collection onset. This collection enhancement increases with drop concentration. Larger concentrations (400 cm−3) show a reduction in collection onset time of as much as 45 min. Including infrared cooling as well as solar heating in the LES and microphysical bin models has a number of effects on the growth of cloud drops. First, shortwave (SW) heating partially offsets cloud-top longwave (LW) cooling, which naturally reduces the influence of LW cooling on drop growth. Second, SW heating dominates over LW cooling at larger drop radii (≳200 μm), which causes moderately sized drops to evaporate. Third, unlike LW cooling, SW heating occurs throughout the cloud deck, which suppresses drop growth. All three of these effects tend to narrow the drop size spectrum. For intermediate drop concentrations (100–200 cm−3), it is shown that SW heating primarily suppresses collection initiation whereas at larger drop concentrations (≳250 cm−3) LW cooling dominates causing enhancements in collection.

Radiative Impacts on the Growth of Drops within Simulated Marine Stratocumulus. Part II: Solar Zenith Angle Variations

Abstract The effects of solar heating at a variety of solar zenith angles (Θo) on the vapor depositional growth of cloud drops, and hence the potential for collection enhancement, is investigated. A large eddy simulation (LES) model is used to predict the evolution of marine stratocumulus clouds subject to changes in Θo. During the course of each simulation, LES output is stored for 600 parcel trajectories and is used to drive an offline microphysical model that includes the influence of radiation on drop growth. Smaller Θo, such as when the sun is overhead, provide strong solar heating, which tends to confine circulations to the cloud layer and leads to long in-cloud residence times for cloud drops. At larger Θo, when solar heating is weak, circulations are stronger and penetrate through the depth of the boundary layer, which causes much shorter in-cloud residence times for cloud drops. Simulations show that this leads to a more rapid collection process in strongly, as compared to weakly solar-heated clouds provided that the liquid water contents of each cloud are similar. When drop vapor growth includes radiative effects, three main results emerge: 1) Solar heating at smaller Θo (0° to 45°) dominates over longwave cooling effects causing a suppression of collection for lower drop concentrations (100 to 200 cm−3). 2) At larger drop concentrations (≳300 cm−3) longwave cooling dominates over solar heating and collection is enhanced. 3) At large Θo (60° to 90°), solar heating is ineffective at modifying the drop size spectrum thus allowing longwave cooling to significantly enhance collection at all drop concentrations above approximately 100 cm−3.

Use of reflectors to enhance the synergistic effects of solar heating and solar wavelengths to disinfect drinking water sources

Aluminum reflectors were added to solar units designed to inactivate faecal microorganisms (faecal coliform, E. coli, enterococci, FRNA coliphage, C. perfringens) in stream water and diluted sewage by the two mechanisms (solar heat, solar UV) known to inactivate microorganisms. During sunny conditions, solar units with and without reflectors inactivated E. coli to <1 CFU/100 ml to meet drinking water standards. Solar units with reflectors disinfected the water sooner by increasing the water temperature by 8-10 degrees C to 64-75 degrees C. However, FRNA coliphages were still detected in these samples, indicating that this treatment may not inactivate pathogenic human enteric viruses. During cloudy conditions, reflectors only increased the water temperature by 3-4 degrees C to a maximum of 43-49 degrees C and E. coli was not completely inactivated. Under sunny and cloudy conditions, the UV wavelengths of sunlight worked synergistically with increasing water temperatures and were able to disinfect microorganisms at temperatures (45-56 degrees C), which were not effective in inactivating microorganisms. Relative resistance to the solar disinfecting effects were C. perfringens > FRNA coliphages > enterococci > E. coli > faecal coliform.