Water Vapor Loss Research Articles

Design, Formulation and Evaluation of Transdermal Drug Delivery System of Budesonide

Budesonide is a highly potent synthetic, nonhalogenated corticosteroid. The mechanism of action of corticosteroids in allergic rhinitis remains unknown, but may involve reductions in number of various mediator cells such as basophils, eosinophils, T-helper cells, mast cells, and neutrophils. In the nasal mucosa, nasal reactivity to allergens, and release of inflammatory mediators and proteolytic enzymes. Budesonide is very effective and quikly acting as it is rapidly and almost completely absorbed after oral administration, but has poor systemic availability (about 10%) due to extensive first-pass metabolism in the liver, mainly by the cytochrome P450 isoenzyme CYP3A4.. The major metabolites, 6-β- hydroxybudesonide and 16-α-hydroxyprednisolone have less than 1% of the glucocorticoid activity of unchanged drug with a terminal half-life of about 2 - 4 hours. Polymeric films containing Eudragit RL 100: Eudragit RS: drug (7:3:1, 7: 2:1) and Ethyl cellulose: PVP: drug (7:3:1, 7:2:1) were selected for transdermal administration based on evaluation studies. These polymeric films were prepared by mercury substrate method employing PEG-400 as plasticizer. Two different penetration enhancers Urea and Dimethyl sulphoxide (DMSO) were employed in the study. The patches in each group were uniform in drug content, thickness. In Vitro drug permeation, moisture absorption and WVTR studies were carried out on these test patches. It was found that at all humidity condition the absorption increases which were linear to the moisture absorbed. In PVA and EUDRAGIT RL 100 patches the water vapor transmission rate was found to be higher at 75% RH, RT conditions. Therefore at both % RH, RT condition the PVA and EUDRAGIT RL 100 patches provides the best resistance to water vapor. Therefore, when applied to animals (in further studies) these patches may provide more occlusion to water vapor loss from skin thus making atmosphere beneath the skin more humid that aid in drug permeation.

Age-induced loss of wound-healing ability in potato tubers is partly regulated by ABA

Wounding of potato (Solanum tuberosum L.) tubers induces the development of a suberized closing layer and wound periderm that resists desiccation and microbial invasion. Wound-healing ability declines with tuber age (storage period). The mechanism of loss in healing capacity with age is not known; however, upregulation of superoxide production, increased ABA biosynthesis and phenylalanine ammonia lyase (PAL) activity in response to wounding are processes critical to the development of a suberized closing layer and wound periderm. Therefore, the role of ABA in modulating the age-induced loss of wound-healing ability of tubers was examined. Non-wounded older tubers had 86% less ABA (dry matter basis) than younger tubers. PAL transcript increased in younger tubers within 24h of wounding, but transcription was delayed by 5days in older tubers. Wound-induced PAL activity increased more rapidly in younger than older tubers. ABA treatment increased PAL expression and activity in tissue from both ages of tubers and restored the 24h transcription time line in older tubers. Moreover, ABA treatment of wounded older tubers enhanced their resistance to water vapor loss following a 6-day wound-healing period. Wound-induced accumulation of suberin poly(phenolic(s)) (SPP) and suberin poly(aliphatic(s)) (SPA) was measurably slower in older versus younger tubers. ABA treatment hastened SPP accumulation in older tubers to match that in younger tubers, but only enhanced SPA accumulations over the initial 4days of healing. Age-induced loss of wound-healing ability is thus partly due to reduced ability to accumulate ABA and modulate the production of SPP through PAL in response to wounding and to dysfunction in the downstream signaling events that couple SPA biosynthesis and/or deposition to ABA. ABA treatment partly restored the healing ability of older tubers by enhancing the accumulation of SPP without restoring wound-induced superoxide forming ability to the level of younger tubers. The coupling of phenolic monomers into the poly(phenolic) domain of suberin was therefore not limited by the diminished wound-induced superoxide production of older tubers.

Effects of Manicure on Water Vapor Loss Through Human Nail in Vivo

Effects of Manicure on Water Vapor Loss Through Human Nail in Vivo

Relative Humidity Effect on the High-Frequency Attenuation of Water Vapor Flux Measured by a Closed-Path Eddy Covariance System

AbstractIn this study the high-frequency loss of carbon dioxide (CO2) and water vapor (H2O) fluxes, measured by a closed-path eddy covariance system, were studied, and the related correction factors through the cospectral transfer function method were calculated. As already reported by other studies, it was found that the age of the sampling tube is a relevant factor to consider when estimating the spectral correction of water vapor fluxes. Moreover, a time-dependent relationship between the characteristic time constant (or response time) for water vapor and the ambient relative humidity was disclosed. Such dependence is negligible when the sampling tube is new, but it becomes important already when the tube is only 1 yr old and increases with the age of the tube. With a new sampling tube, the correction of water vapor flux measurements over a Scots pine forest in Hyytiälä, Finland, amounted on average to 7%. After 4 yr the correction increased strongly, ranging from 10%–15% during the summer to 30%–40% in wintertime, when the relative humidity is typically high. For this site the effective correction improved the long-term energy and water balance.Results suggest that the relative humidity effect on high-frequency loss of water vapor flux should be taken into account and that the effective transfer function should be estimated experimentally at least once per year. On the other hand, this high correction can be avoided by a correct choice and periodic maintenance of the eddy covariance system tube, for example, by cleaning or changing it at least once per year.

Signals involved in tuber wound-healing

The induction and regulation of wound-healing (WH) processes in potato tubers and other vegetables are of great nutritional and economic importance. The rapid accumulation of waxes to restrict water vapor loss and formation of suberin barriers to block infection are crucial components of WH. Recently we determined the regulatory involvement of abscisic acid (ABA) and ethylene in WH. In this addendum we integrate and interpret features from this recent research with additional information on ABA and data on the association of jasmonic acid (JA) in tuber WH. Results show that wounding dramatically increased tuber ethylene production and ABA and JA content. Blockage of wound-induced ABA biosynthesis and ethylene action/biosynthesis showed that ABA is a potent regulator in reduction of water vapor loss and hastening of suberization while ethylene had no discernable effect. The collective results also imply that ethylene has no effect on ABA regulation of WH. JA content in dormant and non-dormant minitubers is very low (≤ l ng gFW-1) but rapidly increases upon wounding then decreases, all before wound-induced ABA or ethylene accumulation reach their maxima. Results gathered to date do not support a role for ethylene in potato tuber WH but do implicate ABA in this process. Although JA content increases rapidly after wounding, its role in tuber WH remains speculative.

Ecohydrological controls on snowmelt partitioning in mixed‐conifer sub‐alpine forests

AbstractWe used co‐located observations of snow depth, soil temperature, and moisture and energy fluxes to monitor variability in snowmelt infiltration and vegetation water use at mixed‐conifer sub‐alpine forest sites in the Valles Caldera, New Mexico (3020 m) and on Niwot Ridge, Colorado (3050 m). At both sites, vegetation structure largely controlled the distribution of snow accumulation with 29% greater accumulation in open versus under‐canopy locations. Snow ablation rates were diminished by 39% in under‐canopy locations, indicating increases in vegetation density act to extend the duration of the snowmelt season. Similarly, differences in climate altered snow‐season duration, snowmelt infiltration and evapotranspiration. Commencement of the growing season was coincident with melt‐water input to the soil and lagged behind springtime increases in air temperature by 12 days on average, ranging from 2 to 33 days under warmer and colder conditions, respectively. Similarly, the timing of peak soil moisture was highly variable, lagging behind springtime increases in air temperature by 42 and 31 days on average at the Colorado and New Mexico sites, respectively. Latent heat flux and associated evaporative loss to the atmosphere was 28% greater for the year with earlier onset of snowmelt infiltration. Given the large and variable fraction of precipitation that was partitioned into water vapour loss, the combined effects of changes in vegetation structure, climate and associated changes to the timing and magnitude of snowmelt may have large effects on the partitioning of snowmelt into evapotranspiration, surface runoff and ground water recharge. Copyright © 2009 John Wiley & Sons, Ltd.

Effect of plastic permeability and exposure to light during storage on the quality of minimally processed broccoli and cauliflower

The impact of lighting on minimally processed broccoli and cauliflower packaged in four different film types (PVC and three P-Plus) has been measured and compared. The effect on the sensory quality of storage at 4 °C in darkness and under lighting was evaluated. The gas concentration in the packages, pH, mesophilic counts and weight loss was also determined. Neither the type of film used for packaging nor the storage conditions led to changes in the evolution of pH or the microorganism count in broccoli and cauliflower. However, exposure to light stimulated stomatic opening facilitate the exchange of gases between the plant tissue and the atmosphere within the packaging. Thus, a considerable loss of water vapor was observed in the packages of both vegetables stored in the presence of illumination. Moreover, exposure to light stimulated respiratory activity so that for the cauliflower, the composition of the atmosphere within the packages varied depending on the permeability of the packaging film used and the storage conditions. However, in the case of the broccoli, the increase in respiratory activity due to the lighting was compensated by the photosynthetic activity which took place in these conditions, in such a way that the composition of the atmosphere inside the packs solely depended on the permeability of the film. This difference in the physiological response conditioned the most suitable kind of packaging film in each case. For cauliflower, in conditions of darkness, P-Plus 120 film proved the most suitable for preserving its sensory qualities, while under conditions of lighting, this film did not prove suitable due to its low permeability. However, in broccoli the different packaging films tested behaved in a very similar way whether stored under lighting or in the dark.

Regulatory involvement of abscisic acid in potato tuber wound-healing

Rapid wound-healing is crucial in protecting potato tubers from infection and dehydration. Wound-induced suberization and the accumulation of hydrophobic barriers to reduce water vapour conductance/loss are principal protective wound-healing processes. However, little is known about the cognate mechanisms that effect or regulate these processes. The objective of this research was to determine the involvement of abscisic acid (ABA) in the regulation of wound-induced suberization and tuber water vapour loss (dehydration). Analysis by liquid chromatography-mass spectrometry showed that ABA concentrations varied little throughout the tuber, but were slightly higher near the periderm and lowest in the pith. ABA concentrations increase then decrease during tuber storage. Tuber wounding induced changes in ABA content. ABA content in wound-healing tuber discs decreased after wounding, reached a minimum by 24 h, and then increased from the 3rd to the 7th day after wounding. Wound-induced ABA accumulations were reduced by fluridone (FLD); an inhibitor of de novo ABA biosynthesis. Wound-induced phenylalanine ammonia lyase activity was slightly reduced and the accumulation of suberin poly(phenolics) and poly(aliphatics) noticeably reduced in FLD-treated tissues. Addition of ABA to the FLD treatment restored phenylalanine ammonia lyase activity and suberization, unequivocally indicating that endogenous ABA is involved in the regulation of these wound-healing processes. Similar experiments showed that endogenous ABA is involved in the regulation of water vapour loss, a process linked to wax accumulation in wound-healing tubers. Rapid reduction of water vapour loss across the wound surface is essential in preventing desiccation and death of cells at the wound site; live cells are required for suberization. These results unequivocally show that endogenous ABA is involved in the regulation of wound-induced suberization and the processes that protect surface cells from water vapour loss and death by dehydration.

Satellite-based estimation of surface vapor pressure deficits using MODIS land surface temperature data

Vapor Pressure Deficit (VPD) is a principle mediator of global terrestrial CO 2 uptake and water vapor loss through plant stomata. As such, methods to estimate VPD accurately and efficiently are critical for ecosystem and climate modeling efforts. Based on prior work relating energy partitioning, remotely sensed land surface temperature (LST), and VPD, we developed simple linear models to predict VPD using saturated vapor pressure calculated from MODIS LST at a number of different temporal and spatial resolutions. We developed and assessed the LST–VPD models using three data sets: (1) instantaneous and daytime average ground-based VPD and radiometric temperature from the Soil Moisture Experiments in 2002 (SMEX02); (2) daytime average VPD from AmeriFlux eddy covariance flux tower observations; and (3) estimated daytime average VPD from Global Surface Summary of Day (GSSD) observations. We estimated model parameters for VPD estimation both regionally (MOD11 A2) and globally (MOD11 C2) with RMSE values ranging from .32 to .38 kPa. VPD was overestimated along coastlines and underestimated in arid regions with low vegetation cover. Also, residuals were larger with higher VPDs because of the non-linear function of saturation vapor pressure with LST. Linear relationships were seen at multiple scales and appear useful for estimation purposes within a range of 0 to 2.5 kPa.

Stable Hydrogen and Oxygen Isotope Composition of Waters from Mine Tailings in Different Climatic Environments

The stable isotope composition of waters (delta2H, delta18O) can be used as a natural tracer of hydrologic processes in systems affected by acid mine drainage. We investigated the delta2H and delta18O values of pore waters from four oxidizing sulfidic mine tailings impoundments in different climatic regions of Chile (Piuquenes at La Andina with Alpine climate, Cauquenes and Carén at El Teniente with Mediterranean climate, and Talabre at the Chuquicamata deposit with hyperarid climate). No clear relationship was found between altitude and isotopic composition. The observed displacement of the tailings pore waters from the local meteoric water line toward higher delta18O values (by approximately +2 per thousand delta18O relative to delta2H) is partly due to water-rock interaction processes, including hydration and O-isotope exchange with sulfates and Fe(III) oxyhydroxides produced by pyrite oxidation. In most tailings, from the saturated zone toward the surface, isotopically different zones can be distinguished. Zone I is characterized by an upward depletion of 2H and 18O in the pore waters from the saturated zone and the lowermost vadose zone, due to ascending diffused isotopically light water triggered by the constant loss of water vapor by evaporation at the surface. In zone II, the capillary flow of a mix of vapor and liquid water causes an evaporative isotopic enrichment in 2H and 18O. At the top of the tailings in dry climate a zone III between the capillary zone and the surface contains isotopically light diffused and atmospheric water vapor. In temperate climates, the upper part of the profile is affected by recent rainfall and zone III may not differ isotopically from zone II.

Influence of Exposure to Light on the Sensorial Quality of Minimally Processed Cauliflower

The impact of lighting on minimally processed cauliflower packaged in 4 different film types (PVC and 3 P-Plus) has been measured and quantified. The effect on the sensorial quality of storage at 4 degrees C in darkness and partial or continuous lighting was evaluated. The gas concentrations in the packages and the weight losses were also determined. Atmosphere composition inside the packages depended on both the permeability of the film used for the packaging and exposure to light. Samples stored with lighting maintained the gaseous exchange between plant tissue and the atmosphere inside the packages for longer periods than in samples kept in darkness. This prompted a greater loss of water vapor as well as the development of atmospheres with low levels of O2 and high levels of CO2 in the samples packed with less permeable films. The most important aspect in sensory evaluation was color. In instrumental color evaluation, coordinates h* and L* were the main means for estimating color evolution. The presence of light accelerated browning in the cut zones. The development of abnormal coloring in these areas marked the end of shelf life for minimally processed cauliflower. Among the sensory attributes studied, color was the most affected by exposure to light. Samples packed in P-Plus 120 film displayed the lowest level of color deterioration in the cut zones. However, under lit conditions, the low permeability of this film caused atmospheres with very low O2 contents and high CO2 contents. These atmospheres produced a loss of texture and the development of off-odors.

Implementation of microfluidic devices at a transparency

We have developed a scanning laser manufacturing technique to produce microfluidic structures directly on photocopy transparency films. The reasons for the selection of transparency include (i) its insignificant water diffusion and vapor loss characteristics, (ii) its reduced viscoelastic behavior and (iii) its very low cost. The stiffness of the transparency membrane can be carefully tailored by adjusting laser ablation power. To show the feasibility of the approach, we have fabricated membrane valves on the transparency, and demonstrated a peristaltic micro-pumping system. Our investigation offers the potential for developing new types of very low-cost disposable devices including flexible microfluidic systems.

Effects of environmental salinity on carbon isotope discrimination and stomatal conductance in Spartina grasses

MEPS Marine Ecology Progress Series Contact the journal Facebook Twitter RSS Mailing List Subscribe to our mailing list via Mailchimp HomeLatest VolumeAbout the JournalEditorsTheme Sections MEPS 313:305-310 (2006) - doi:10.3354/meps313305 Effects of environmental salinity on carbon isotope discrimination and stomatal conductance in Spartina grasses Brian R. Maricle*, Raymond W. Lee School of Biological Sciences, Washington State University, PO Box 644236, Pullman, Washington 99164-4236, USA *Email: bmaricle@mail.wsu.edu ABSTRACT: High salinity levels have long been recognized as an important environmental factor influencing plant growth and performance. Salt stress and concomitant water stress are likely to affect photosynthesis by reductions in stomatal conductance necessary to prevent loss of water vapor. Despite inundation with saline water, salt marsh communities exhibit high primary productivity. This study tested the effects of 0 to 40‰ salinity on leaf carbon isotope discrimination (Δ), leaf stomatal conductance (gs), and leaf conductance to CO2 (gCO2) in the emergent estuarine C4 grasses Spartina alterniflora, S. anglica, and S. patens. Δ increased with increasing salinity in greenhouse and growth chamber experiments. gs and gCO2 peaked at moderate salinity levels (10 to 20‰) but significantly decreased at higher salinities in all species. KEY WORDS: Salt stress · Photosynthesis · Spartina · δ13C · Stable isotopes Full text in pdf format PreviousExport citation RSS - Facebook - Tweet - linkedIn Cited by Published in MEPS Vol. 313. Online publication date: May 11, 2006 Print ISSN: 0171-8630; Online ISSN: 1616-1599 Copyright © 2006 Inter-Research.

On the sublimation of ice particles on the surface of Mars; with applications to the 2007/8 Phoenix Scout mission

Experimental studies related to the sublimation of ice, in bulk or as small particles, alone or mixed with dust similar to that expected on the surface of Mars, are reported. The experiments, a cloud physics particle sublimation model, and a convection model presented by Ingersoll, all indicate a strong dependence of sublimation rate on temperature, and this appears to be the dominant factor, assuming that the relative humidity of the air is fairly low. In addition the rate of loss of water vapour appears to depend primarily on exposed surface area and less on particle size and the total mass of the sample, or the mass of ice in the sample. The 2007/8 Phoenix Scout mission plans to obtain and analyse samples of sub-surface ice from about 70° N on Mars. A concern is that these samples, in the form of ice chips of size about 1 mm diameter, could be prone to sublimation when exposed for prolonged periods (many hours) to a relatively warm and dry atmosphere. Our laboratory simulations confirm that this could be a problem if particles are simply left lying on the surface, but also indicate that samples kept suitably cold and collected together in confined piles will survive long enough for the collection and delivery (to the analysis instruments) procedure to be completed.

Comet 67P/Churyumov–Gerasimenko: Modeling of orientation and structure

The comet 67P/Churyumov–Gerasimenko is the current target of the mission Rosetta, initially planned to investigate comet 46P/Wirtanen. These two comets have similar orbits, except the distance to the Sun at perihelion, but different orbital histories and different masses. Thus, structures of the nuclei can be significantly different. The evolution of comet Wirtanen was simulated by several authors, while comet Churyumov–Gerasimenko became an object of high interest only recently and is not well investigated. In the present work we simulate the evolution of the nucleus, down to tens of meters below the surface, using an extended version of the model previously applied for comet Wirtanen [Kossacki et al., 1999. Comet 46P/Wirtanen: evolution of the subsurface layer. Icarus 142, 202–218.]. The model includes strengthening of the nucleus due to sintering of the ice grains. Simulations are performed for different latitudes, accounting for the evolution of the orbit and for changes of the nucleus orientation, as well as diurnal and seasonal changes of insolation. The calculated loss of water vapor from the comet is integrated over the nucleus surface and is compared with the observational data. We have found, that the sublimation through the dust mantle can be large enough to reproduce the profile of the total water production as a function of time from perihelion. The required dependence of thickness of the dust layer on latitude qualitatively matches present distribution of the absorbed solar flux. The non-gravitational acceleration in the comet motion together with the simulated sublimation flux are used in order to estimate the mass and the bulk density of the nucleus.

The 13–14 December 2001 IMPROVE-2 Event. Part III: Simulated Microphysical Budgets and Sensitivity Studies

Abstract This paper investigates the microphysical pathways and sensitivities within the Reisner-2 bulk microphysical parameterization (BMP) of the fifth-generation Pennsylvania State University–National Center for Atmospheric Research (PSU–NCAR) Mesoscale Model (MM5) for the Improvement of Microphysical Parameterization through Observational Verification Experiment (IMPROVE)-2 field experiment on 13–14 December 2001. A microphysical budget over the windward slope at 1.33-km horizontal grid spacing was calculated, in which the importance of each microphysical process was quantified relative to the water vapor loss (WVL) rate. Over the windward Cascades, the largest water vapor loss was associated with condensation (73% of WVL) and snow deposition (24%), and the windward surface precipitation resulted primarily from accretion of cloud water by rain (27% of WVL), graupel fallout and melt (19%), and snowmelt (6%). Two-thirds of the snow generated aloft spilled over into the lee in an area of model overprediction, resulting in windward precipitation efficiency of only 50%. Even with the large amount of precipitation spillover, the windward precipitation was still overpredicted in many locations. A series of experiments were completed using different snowfall speeds, cloud water autoconversion, threshold riming values for snow to graupel autoconversion, and slope intercepts for snow. The surface precipitation was most sensitive to those parameters associated with the snow size distribution and fall speed, while decreasing the riming threshold for snow to graupel conversion had the greatest positive impact on the precipitation forecast. All simulations overpredicted cloud water over the lower windward slopes, had too little cloud water over the crest, and had too much ice at moderate-to-large sizes aloft. Riming processes were important, since without supercooled water there were bull’s-eyes of spurious snow spillover over the lee slopes.

Potential impact of convective fracture venting on salt-crust buildup and ground-water salinization in arid environments

We present a conceptual model by which surface-exposed fractures could be the main source of aquifer salinization under arid conditions. Fractures in thick vadose zones of low permeability are considered the major conduit for aquifer recharge in arid and semi-arid lands. Evaporation of pore water from within fractures is hypothesized to be enhanced by convective air circulation within the fracture that vents moisture to the atmosphere. This phenomenon also enhances lateral movement of pore water from the adjacent matrix towards the fracture opening. Subsequent evaporation results in salt precipitation within the fracture that can be conducted to the aquifer during the rainy season. The proposed model suggests that most of the water vapor loss from fractures is driven by an inversion in the thermal gradient of the adjacent matrix during the cold nights rather than the hot days. This conceptual model is investigated theoretically and tested in a series of preliminary experimental studies.

Guard Cells: Transcription Factors Regulate Stomatal Movements

Recent work shows that transcription factors are necessary for stomatal movements in plants. Different members of the plant-specific R2R3-MYB transcription factor family are required for mediating stomatal opening in response to light and stomatal closure in response to darkness.

Regional and developmental variations of blood vessel morphometry in the chick embryo chorioallantoic membrane

Avian eggs contain all the necessary materials for embryonic development except for oxygen, which diffuses in from the environment via pores in the hard, calcified eggshell to the chorioallantoic membrane (CAM), the respiratory organ, which is rich in blood vessels. An air cell is formed at the blunt pole of the egg between the two membranes of the eggshell and enlarges during incubation due to water vapor loss. In this study of the CAM of chicken eggs, we compared blood vessel numerical density [N(A(v))], area fraction of blood vessels [A(A(v))], CAM thickness (D(CAM)), total length of blood vessels (L) and surface area of the CAM attached to the eggshell (CAMre) with those under the air cell (CAMac) during incubation. We found that N(A(v)), A(A(v)), D(CAM) and L of the CAM increase with embryonic age and development. The N(A(v)), A(A(v)) and L under the air cell were higher in relation to the rest of the CAM at all ages tested, while the D(CAM) under the air cell was always lower than around the rest of the egg. Since the eggshell over the air cell has a relatively greater porosity, and the respiratory gas exchange ratio there is higher than at other areas of the egg, there is a correlation between all the above morphometric data and the eggshell porosity. This suggests optimization of embryonic gas exchange in the chicken egg. We would like to propose that, during natural incubation, an increased gas diffusion under the air cell, together with increased blood vessel numerical density, may compensate for covering of the central part of the eggshell by the incubating parent.

Bulk Microphysical Sensitivities within the MM5 for Orographic Precipitation. Part II: Impact of Barrier Width and Freezing Level

This paper investigates the impact of barrier width and freezing level on the microphysical processes and pathways within the Reisner2 bulk microphysical parameterization (BMP) using a two-dimensional version of the fifth-generation Pennsylvania State University‐National Center for Atmospheric Research (PSU‐NCAR) Mesoscale Model (MM5). As the barrier half-width is decreased incrementally from 50 km (relatively wide mountain) to 10 km (narrow mountain) for a deep orographic cloud and a 750-mb freezing level, the percentage of water vapor loss (WVL) rate over the windward slope leading to snow deposition decreases from 23% to 7%, while condensation increases from 74% to 93% of WVL rate. A narrow (10 km) barrier has less snow aloft, twice as much cloud water over the windward slope, and a shallow region of intense riming over the crest that results in twice as much graupel as the wide (50 km) barrier. It is found that a relatively wide barrier ( $30 km half-width) allows more time for snow growth aloft; therefore, it is more sensitive to snow parameters over the windward slope such as the slope intercept for number concentration and fall speeds. In contrast, a narrower barrier is more sensitive to rain and graupel processes, such as the cloud water autoconversion and graupel fall speeds. The wide barrier has a larger sensitivity to cloud water processes when the freezing level is elevated to 500 mb, while the narrow barrier is more sensitive to snow processes when the freezing level is lowered to 1000 mb. For a 1000-mb freezing level, the lack of riming and accretion reduces the rapid increase in maximum precipitation that is shown to occur when the barrier halfwidth is reduced from 20 and 10 km for a higher freezing level.