Snow Pile Research Articles

Assessing the key concerns in snow storage: a case study for China

Abstract. Snow security plays a crucial role in ensuring the success of winter sports events and supporting the ski industry. One effective approach to enhancing snow reliability is through snow storage. Despite its potential benefits, investigations of snow storage in China have been limited. To address this gap, we implemented snow storage covered with geotextiles at two venues, namely the Big Air Shougang (BAS) in Beijing for the Beijing 2022 Winter Olympic Games and the National Biathlon Center (NBC) in Chongli for the Beijing 2022 Winter Paralympic Games, in response to possible extreme meteorological conditions. To assess the key concerns associated with snow storage, ablation (the process of snow loss) and snow properties, we introduced a fine-snow-pile monitoring system and the SNOWPACK model. Our observations revealed that, by 18 February, the snow pile at BAS had lost 158.6 m3 of snow (equivalent to 6.7 % of the initial volume). Subsequently, the accelerated ablation was influenced by meteorological conditions and a thin geotextile layer. Between 16 January and 15 April, the snow pile at BAS experienced a total loss of 1242.9 m3 of snow (corresponding to 52.7 % of the original volume). Regarding snow properties, no significant variations were modeled at the study sites, except for the upper part of the snow piles. Notably, the evaporation of the geotextiles contributed to slowing the ablation process. Consequently, we discourage the use of impermeable coverage schemes for snow storage. Instead, the thickness of the cover played a vital role in preserving the snow pile. At Beijing and Chongli, the 0.7 and 0.4 m thick cover layers, respectively, were found to protect approximately half of the snow pile height over the summer season. Importantly, the evolution of snow properties was consistent across the different cover thicknesses. The findings of our study have implications for the ski industry in China, as they provide valuable insights into snow storage techniques and their impact on snow reliability.

Demonstration of Snow Removal Work by Wheel Loader in an Environment Surrounded by Obstacles

Snow removal work using construction equipment faces problems such as a shortage of skilled operators owing to the declining birthrate and aging population, work in dangerous areas, and accidents caused by a lack of concentration during long work hours. To improve the working environment, research and development of automation of construction equipment are actively conducted. Therefore, in this study, we aim to generate a driving path for wheel loaders for snow removal work in a work environment surrounded by obstacles, such as walls and fences. Furthermore, the proposed method considers the changing shape of the snow piles during the removal. We experimentally verified that snow removal could be performed using an actual wheel loader on the route generated by the proposed simulation.

Designing Machine Learning Algorithm for Autonomous Driving in the Snow

Autonomous vehicles have evolved to make decisions with great confidence and accuracy. Systems like the Waymo self-driving clearly have the ability to control a vehicle with level 4 autonomy under good conditions where lane markings and other driving guides like road signs are clearly visible [2]. Elon Musk has announced that Tesla autopilot should reach level 4 in 2023 [3]. However, many such systems fail to perform at a similar level in non-perfect weather conditions. The most difficult such weather appears to be a snowy climate as the vehicle significantly underperforms and the autonomous functionality is often not applicable [1]. This paper aims to train a model capable of navigating snowy weather by collecting data pertaining specifically to this weather, including unorthodox visual cues to stand in place of road markings. Such cues include tire tread marks and surrounding snow piles. These serve as a viable substitute for lane markings, allowing the vehicle to operate safely while mimicking human driving tendencies. Such a model is able to effectively drive in both clear and snowy weather when tested in simulation software. We consider a model effective for the purposes of this study in the snow when it is able to execute a full turn before failure.

Impacts of snow-farming on alpine soil and vegetation: A case study from the Swiss Alps

Snow-farming is one of the adaptive strategies used to face the snow deficit in ski resorts. We studied the impact of a shifting snow-farming technique on a pasture slope in Adelboden, Switzerland. Specifically, we compared plots covered by a compressed snow pile for 1.5, 2.5 or 3.5 years, which then recovered from the snow cover for three, two or one vegetation seasons, respectively, with control plots situated around the snow pile.In plots with >1.5 years of compressed snow pile, plant mortality was high, recovery of vegetation was very slow, and few plant species recolonized the bare surface. Soil biological activity decreased persistently under prolonged snow cover, as indicated by reduced soil respiration. The prolonged absence of fresh plant litter and root exudates led to carbon (C) limitation for soil microbial respiration, which resulted in a significant decrease in the ratio of total organic carbon to total nitrogen (TOC/TN) under the snow pile.Microbial C, nitrogen (N) and phosphorus (P) immobilization decreased, while dissolved N concentration increased with compressed snow cover. Longer snow cover and a subsequent shorter recovery period led to higher microbial C/P and N/P but lower microbial C/N. Nitrate and ammonium were released massively once the biological activity resumed after snow clearance and soil aeration.The soil microbial community composition persistently shifted towards oxygen-limited microbes with prolonged compressed snow cover. This shift reflected declines in the abundance of sensitive microorganisms, such as plant-associated symbionts, due to plant mortality or root die-off. In parallel, resistant taxa that benefit from environmental changes increased, including facultative anaerobic bacteria (Bacteroidota, Chloroflexota), obligate anaerobes (Euryarchaeota), and saprophytic plant degraders.We recommend keeping snow piles in the same spot year after year to minimize the area of the impacted soil surface and plan from the beginning soil and ecosystem restoration measures.

Comparative Effectiveness of an Artificial Air Pocket Device to Delay Asphyxiation in Supine Individuals Critically Buried in Avalanche Debris

Approximately 70% of individuals critically buried in avalanche debris die within 35 minutes as a result of asphyxial cardiac arrest. An artificial air-pocket device (AAPD) that separates inhaled air from exhaled air may delay the onset of severe hypoxemia and eventual asphyxia during snow burial. To investigate the efficacy of a new AAPD during snow burial in a supine position. This comparative effectiveness trial was performed in winter 2016 with data analysis in November 2016 and November 2022. Each trial used a simulated critical avalanche burial scenario, in which a trough was dug in a snow pile and an additional air pocket of 0.5 L volume was punched into the lateral wall for each control trial. All participants were buried in a supine position. Trials could be voluntarily terminated at any time, with a maximum length of 60 minutes; trials were automatically terminated if the participant's peripheral oxygen saturation (Spo2) dropped to less than 84%. Each participant conducted 2 trials, one in which they breathed into the AAPD (intervention trial) and the other in which they breathed into the prepared air pocket (control trial). Measurements included Spo2, cerebral oxygenation, ventilatory parameters, respiratory gas concentrations, and visual-analogue scales. Kaplan-Meier survival curves and rank test for matched survival data were used to analyze the total burial time in each trial. A total of 13 volunteers (9 men; mean [SD] age, 33 [8] years) were exposed to the intervention and control trials. Intervention trials were terminated less often (2 of 13 trials) as a result of hypoxemia than control trials (11 of 12 trials). Similarly, survival curves showed a longer duration of burial in the intervention compared with the control trials for the time to reach an Spo2 less than 84% (rank test for matched survival data: P = .003). The intervention trials, compared with the control trials, also had slower rates of decrease in fraction of inspired oxygen (mean [SD] rate, -0.8 [0.4] %/min vs -2.2 [1.2] %/min) and of increase in fraction of inspired carbon dioxide (mean [SD] rate, 0.5 [0.3] %/min vs 1.4 [0.6] %/min) and expired ventilation per minute (mean [SD] rate, 0.5 [1.0] L/min2 vs 3.9 [2.6] L/min2). This comparative effectiveness trial found that the new AAPD was associated with delaying the development of hypoxemia and hypercapnia in supine participants in a critical burial scenario. Use of the AAPD may allow a longer burial time before asphyxial cardiac arrest, which might allow longer times for successful rescue by companions or by prehospital emergency medical services.

Assessment of trace elements pollution in snow piles removed from residential areas in Perm, Russia

Atmospheric deposition, vehicular transportation and de-icing agents are major sources polluted snow in urban. This study investigates the current trace elements concentrations of snow and de-icing using ICP-MS, and phytotoxicity using three vascular plants in snow. The study assesses the contamination, classification and phytotoxicity of snow quality removed from roads of residential areas and piled on children’s playgrounds in residential territories. The research found that according to Russian environmental quality standard for water has been identified the exceeding trace elements in snow by W, Se, Mn, Cu, V, Mo, Ni and Zn. The pollution indices ( PLI, CF and Zc) were identified pollution level of snow piles from moderate contamination to very high contamination. Based on average germination index values for Sinapis alba L., Lepidium sativum L., and Triticum aestivum L., the degree of inhibition in snow piles varied from no inhibition to strong inhibition. The trace elements content in de-icing “Galit А” and salt sand mix are defined in the following descending order: Zn > Mn > Ba > V > Rb > Sr and Mn > Ba > Cr > V > Sr > Ni, respectively. High concentrations of trace elements in snow piles are a source of environmental pollution. To prevent snow storage and disposal in residential areas should be involved in future studies of environmental pollution and circular economy, so that environmental managers can reduce threats to the environment and public health, as well as initiate circular economy projects in urban areas.

Ari Folman’s Made in Israel (2001): Traces of Trauma in the Israeli Cinema Landscape

In the Israeli collective memory, the Yom Kippur’s battles in the Golan Heights have become synonymous with a long lasting national scar that fails to disappear. Interestingly, until the release of Yaron Zilberman’s recent television series Valley of Tears (She’at Ne’Ila, 2020), this war, which was traditionally associated with the pictured northern landscape, had appeared in few documentaries, but was almost absent from Israeli feature films. This article analyzes one of the very few attempts to deal with this memory, Ari Folman’s feature film Made in Israel (2001). Using a science fiction narrative structure, Folman adopts historian Anita Shapira’s contention about the link between this war and the Holocaust, because both confronted the Jewish people with its fear of extermination. His narrative invites the viewer to participate imaginatively in a road movie set against the snow-covered landscapes of the Golan Heights, where a number of hitmen attempt to catch the last surviving Nazi and bring him to trial in Jerusalem. Interestingly, what begins as a Zionist mission in the hegemonic spaces of the State of Israel gradually transforms into various European landscapes as the snow piles up and the Nazi feels increasingly at home.

Estimating Pollution Loads in Snow Removed from a Port Facility: Snow Pile Sampling Strategies

Choosing the appropriate sampling strategy is significant while estimating the pollutant loads in a snow pile and assessing environmental impacts of dumping snow into water bodies. This paper compares different snow pile sampling strategies, looking for the most efficient way to estimate the pollutant loads in a snow pile. For this purpose, 177 snow samples were collected from nine snow piles (average pile area − 30 m2, height − 2 m) during four sampling occasions at Frihamnen, Ports of Stockholm’s port area. The measured concentrations of TSS, LOI, pH, conductivity, and heavy metals (Zn, Cu, Cd, Cr, Pb, and V) in the collected samples indicated that pollutants are not uniformly distributed in the snow piles. Pollutant loads calculated from different sampling strategies were compared against the load calculated using all samples collected for each pile (best estimate of mass load, BEML). The results/study showed that systematic grid sampling is the best choice when the objective of sampling is to estimate the pollutant loads accurately. Estimating pollutant loads from single snow column samples (collected at a point from the snow pile through the entire depth of the pile) produced up to 400% variation from BEML, whereas samples composed by mixing volume-proportional subsamples from all samples (horizontal composite samples) produced only up to 50% variation. Around nine samples were required to estimate the pollutant loads within 50% deviation from BEML for the studied snow piles. Converting pollutant concentrations in snow to equivalent concentrations in snowmelt and comparing it with available guideline values for receiving water, Zn was identified as the critical pollutant.

Not avian but mammalian scavengers efficiently consume carcasses under heavy snowfall conditions: a case from northern Japan

Interest in trophic interactions and ecosystem functions derived from carcass consumption by scavengers has been increasing. Here, we conducted the first evaluation of scavenging processes in an ecosystem with heavy snow, located in northern Japan, which is characterized by the limitations of visual and odor cues to detect carcasses. In this study, we verified the behavioral traits and assemblage compositions of avian and mammalian scavengers, which consumed six different carcass types buried in snow. We measured the visits of scavengers using camera traps between 2010 and 2020. The total scavenger richness observed was relatively low (only 12 species) compared to warmer biomes. We observed seven avian scavenger species, but their visit frequencies were extremely low compared with those of nocturnal mammalian scavengers, such as raccoon dogs (Nyctereutes procyonoides) and martens (Martes melampus), which were able to detect carcasses more rapidly and frequently. Our findings imply that large snow piles significantly prevent avian scavengers from detecting carcasses. In contrast, the snow piles could protect carcasses from the freezing air and ensure the occurrence of a basal level of microbial decomposition, possibly leading to carcass decomposition. This probably results in carcasses still providing odor cues for mammalian scavengers with heightened sense of smell. Moreover, considering the high carcass consumption rate (91.3% of full-body carcass; n = 23) and short carcass detection times (approximately 90 h) observed, it is possible that scavenging in heavy snowfall conditions has become systematically integrated into the foraging tactics of many mammalian scavengers.

“Beyond a Snow Pile”: Najīb Surūr’s Challenging Reading of the Egyptian Literary Canon in Riḥlah Fī Thulāthiyyat Najīb Maḥfūẓ

Abstract This study of the Egyptian intellectual Najīb Surūr’s critical essay, Riḥlah fī Thulāthiyyat Najīb Maḥfūẓ (c. 1978; A Journey into Najīb Maḥfūẓ’s Trilogy) argues that this underexplored work of Surūr is a brave assessment of the Egyptian literary canon of the 1950s. The argument finds justification in the author’s unique mastery of irony, and his vigorous textual engagement with Maḥfūẓ’s widely acclaimed masterpiece. Throughout his essay, liberated from a “snow pile” of sensational success, Surūr dives into Maḥfūẓ’s novel Bayna al-Qaṣrayn, in order to bolster his conviction that all authors and genres deserve in-depth analyses. Arguing the viability of applying the Constance School’s Reception Theory in evaluating Surūr’s revolutionary reading, this paper seeks to resituate new aesthetical and ideological paradigms in criticism within the broader context of extra literary/intraliterary dynamics that give birth to competing works of fiction. Surūr’s effort also highlights a compelling mismatch between young authors’ de jure inventive ambitions and their de facto conciliation with previous models.

Optimization of over-summer snow storage at midlatitudes and low elevation

Abstract. Climate change, including warmer winter temperatures, a shortened snowfall season, and more rain-on-snow events, threatens nordic skiing as a sport. In response, over-summer snow storage, attempted primarily using woodchips as a cover material, has been successfully employed as a climate change adaptation strategy by high-elevation and/or high-latitude ski centers in Europe and Canada. Such storage has never been attempted at a site that is both low elevation and midlatitude, and few studies have quantified storage losses repeatedly through the summer. Such data, along with tests of different cover strategies, are prerequisites to optimizing snow storage strategies. Here, we assess the rate at which the volume of two woodchip-covered snow piles (each ∼200 m3), emplaced during spring 2018 in Craftsbury, Vermont (45∘ N and 360 m a.s.l.), changed. We used these data to develop an optimized snow storage strategy. In 2019, we tested that strategy on a much larger, 9300 m3 pile. In 2018, we continually logged air-to-snow temperature gradients under different cover layers including rigid foam, open-cell foam, and woodchips both with and without an underlying insulating blanket and an overlying reflective cover. We also measured ground temperatures to a meter depth adjacent to the snow piles and used a snow tube to measure snow density. During both years, we monitored volume change over the melt season using terrestrial laser scanning every 10–14 d from spring to fall. In 2018, snow volume loss ranged from 0.29 to 2.81 m3 d−1, with the highest rates in midsummer and lowest rates in the fall; mean rates of volumetric change were 1.24 and 1.50 m3 d−1, 0.55 % to 0.72 % of initial pile volume per day. Snow density did increase over time, but most volume loss was the result of melting. Wet woodchips underlain by an insulating blanket and covered with a reflective sheet were the most effective cover combination for minimizing melt, likely because the aluminized surface reflected incoming short-wave radiation while the wet woodchips provided significant thermal mass, allowing much of the energy absorbed during the day to be lost by long-wave emission at night. The importance of the pile surface-area-to-volume ratio is demonstrated by 4-fold lower rates of volumetric change for the 9300 m3 pile emplaced in 2019; it lost <0.16 % of its initial volume per day between April and October, retaining ∼60 % of the initial snow volume over summer. Together, these data demonstrate the feasibility of over-summer snow storage at midlatitudes and low elevations and suggest efficient cover strategies.

Laboratory Melting of Late-Winter Urban Snow Samples: The Magnitude and Dynamics of Releases of Heavy Metals and PAHs

Laboratory snow melting experiments were conducted with actual late-winter snow samples, collected just before the final snowmelt, in two similar northern Swedish cities, Luleå and Umeå, to investigate releases of the selected heavy metals (HM) (Cu, Pb, Zn, and Cd) and 16 USEPA PAHs from melting snow. Metal concentrations were determined in three fractions: total, dissolved, and truly dissolved (defined as the fraction passing through a 3-kMWCO ultrafilter). Total HM concentrations in snowmelt were rather high at both sites and reflected the accumulation of pollutants in the roadside snowbanks over a period of about 5 months: Cd = 0.43, Cu = 303, Pb = 41.9, Zn = 817 (μg/l), and TSS = 2000 (mg/l) in Luleå samples and Cd = 1.87, Cu = 905, Pb = 165, Zn = 3150 (μg/l), and TSS = 4800 (mg/l) in Umeå samples. The difference between metal and TSS concentrations at the two sites of similar characteristics was attributed to a smaller volume snowbank in Umeå. The dissolved HM concentrations represented relatively small fractions of the total concentrations (0.3–6.9% in Luleå and 0.01–3.1% in Umeå). The truly dissolved fraction represented 71–90% of the dissolved fraction in Luleå and 74–98% in Umeå. At both sites, the dissolved fractions exhibited preferential elution from the laboratory snow piles. The PAHs studied (16 US EPA PAHs) were mostly particulate bound, with only 5–12% of the total burden contributed by the meltwater, and most dissolved concentrations below the reporting limits. PAH concentrations in the Luleå samples were about one-third to one-fourth of those in Umeå. In general, the releases of PAHs from the snowbank were delayed, compared with releases of meltwater, and showed similar release patterns as TSS.

Here on Earth

Here on Earth Chad Abushanab (bio) The field behind our house tonightreminds me of an empty bedwith drifts of snow like wrinkled sheetsand shadows where you laid your head. A month and six days since you left,and night is when I feel you most.Sleep won’t come. I sit outsidetrying to ignore your ghost. Instead, the snow piles up. The woodsbeyond the field grow darker still.I shut my eyes against the cold,swallow another sleeping pill, and brace myself to face the numbwhite space, the bed you’re missing from. [End Page 128] Chad Abushanab chad abushanab is the author of The Last Visit, winner of the Donald Justice Poetry Prize, published by Autumn House Press in 2019. His poems have appeared in the New York Times Magazine, Southern Poetry Review, Shenandoah, Best New Poets, the Believer, and 32 Poems. He earned his PhD in English and creative writing at Texas Tech University. He lives in Iowa City. Copyright © 2019 University of North Carolina Wilmington

Characterization and temporal variation of urban runoff in a cold climate - design implications for SuDS

ABSTRACTThis paper characterizes stormwater runoff in a coastal cold climate urban area regarding metal fractionation and particle size distribution to understand the implications for sustainable urban drainage system (SuDS) design. Strong temporal and spatial variations were found for all studied parameters. Suspended and dissolved solids showed up to 10-fold and 44-fold increase, respectively, during salting periods (air temperature <0 °C). Metals were nearly solely associated with the suspended fraction (>1.2 µm), which increased during the salting periods (>97%). Use of snow-tyres and de-icers (gritting sand and NaCl) are more likely to explain the temporal fluctuations, rather than contributions from nearby snow piles. Residential streets might serve as a source of pollutants during the winter months when street sweeping is minimal. These results imply that protection against clogging from excessive sediment loads and use of salts during winter should be the primary focus for SuDS design.

Snow farming: conserving snow over the summer season

Abstract. Summer storage of snow for tourism has seen an increasing interest in the last years. Covering large snow piles with materials such as sawdust enables more than two-thirds of the initial snow volume to be conserved. We present detailed mass balance measurements of two sawdust-covered snow piles obtained by terrestrial laser scanning during summer 2015. Results indicate that 74 and 63 % of the snow volume remained over the summer for piles in Davos, Switzerland and Martell, Italy. If snow mass is considered instead of volume, the values increase to 83 and 72 %. The difference is attributed to settling and densification of the snow. Additionally, we adapted the one-dimensional, physically based snow cover model SNOWPACK to perform simulations of the sawdust-covered snow piles. Model results and measurements agreed extremely well at the point scale. Moreover, we analysed the contribution of the different terms of the surface energy balance to snow ablation for a pile covered with a 40 cm thick sawdust layer and a pile without insulation. Short-wave radiation was the dominant source of energy for both scenarios, but the moist sawdust caused strong cooling by long-wave emission and negative sensible and latent heat fluxes. This cooling effect reduces the energy available for melt by up to a factor of 12. As a result only 9 % of the net short-wave energy remained available for melt. Finally, sensitivity studies of the parameters thickness of the sawdust layer, air temperature, precipitation and wind speed were performed. We show that sawdust thickness has a tremendous effect on snow loss. Higher air temperatures and wind speeds increase snow ablation but less significantly. No significant effect of additional precipitation could be found as the sawdust remained wet during the entire summer with the measured quantity of rain. Setting precipitation amounts to zero, however, strongly increased melt. Overall, the 40 cm sawdust provides sufficient protection for mid-elevation (approx. 1500 m a.s.l.) Alpine climates and can be managed with reasonable effort.

Sub-picosecond chirped laser pulse-induced airflow and water condensation in a cloud chamber

Sub-picosecond chirped laser pulse-induced airflow and water condensation were investigated in a cloud chamber. The results indicate that the positively chirped sub-picosecond laser pulses generate a more uniform intensity distribution inside the plasma column, leading to a weaker airflow and an elliptic-shaped snow pile. The negatively chirped sub-picosecond laser pulses generate a spark-like intensity distribution inside the plasma column, which produces a wider range of airflow and a round snow pile. The amount of snow weight and the concentration of NO3− are found to be dependent on the intensity distribution inside the plasma column. The visibly stronger plasma column generates much more snow and a higher concentration of NO3−. These experimental results provide a reference for sub-picosecond laser-induced water condensation in realistic atmospheric conditions.

Determination of snowmaking efficiency on a ski slope from observations and modelling of snowmaking events and seasonal snow accumulation

Abstract. The production of Machine Made (MM) snow is now generalized in ski resorts and represents the most common method of adaptation for mitigating the impact of a lack of snow on skiing. Most investigations of correlations between snow conditions and the ski industry's economy focus on the production of MM snow though not one of these has taken into account the efficiency of the snowmaking process. The present study consists of observations of snow conditions (depth and mass) using a Differential GPS method and snow density coring, following snowmaking events and seasonal snow accumulation in Les Deux Alpes ski resort (French Alps). A detailed physically based snowpack model accounting for grooming and snowmaking was used to compute the seasonal evolution of the snowpack and compared to the observations. Our results show that approximately 30 % of the water mass can be recovered as MM snow within 10 m from the center of a MM snow pile after production and 50 % within 20 m. Observations and simulations on the ski slope were relatively consistent with 60 % (±10 %) of the water mass used for snowmaking within the limits of the ski slope. Losses due to thermodynamic effects were estimated in the current case example to be less than 10 % of the total water mass. These results suggest that even in ideal conditions for production a significant fraction of the water used for snowmaking can not be found as MM snow within the limits of the ski slope with most of the missing fraction of water. This is due to site dependent characteristics (e.g. meteorological conditions, topography).

Plowing paradise: snow clearing and urban solar radiation absorption

Urban heat islands result from human modification of land surfaces. Snow cover reduces heating due to its reflectivity; however, urban snow is quickly plowed, thus altering surface radiative properties. The goal of this study was to evaluate the extent to which municipal snow removal affects the magnitude of solar input associated with changes in the radiation balance. Incoming and reflected shortwave radiation, surface radiating temperature, air temperature, and snow depth were measured with portable devices at eight sites in Syracuse, New York. Sites were classified as cleared, undisturbed, or snow piles. Measurements were taken following fresh snowfall, and continuing until snow had melted. A HOBO weather station provided hourly baseline conditions. Longevity of snow varied across snow site types, with greater persistence when in piles and on open areas. Albedo was reduced and surface temperatures were higher over cleared areas. The difference between absorbed energy due to clearing was quantified using an albedo regression model for undisturbed sites and comparing these to average reflectivity of cleared surfaces. The magnitude difference over the study period ranged from 841 million to 1670 million MJ. Snow plowing is therefore a significant source of additional energy that enhances the winter urban heat island.

Differently patterned airflows induced by 1-kHz femtosecond laser filaments in a cloud chamber

Airflow induced by femtosecond laser (800 nm/1 kHz/25 fs) filamentation with different lengths was investigated in a laboratory cloud chamber. Various filament lengths were generated by adjusting laser energy and lens focal length. It was found that airflow patterns are closely related to filament intensity and length. Intense and long filaments are beneficial in updraft generation with large vortices above the filament, while intense and short filaments tend to promote the formation of well-contacted vortices below the filament. Differently patterned airflows induced elliptical snow piles with different masses. We simulated airflow in a cloud chamber numerically taking laser filaments as heat sources. The mechanisms of differently patterned airflow and snow formation induced by filaments were discussed.

Hybrid‐based snow simulation and snow rendering with shell textures

AbstractIn this study, we develop a system for interactive snow simulation and rendering. Snow is modeled as a hybrid structure that handles movable snow and static snow separately. We develop a simple approach to convert between these two types of snow. Movable snow is represented by a set of particles, whereas static snow is modeled as grid cells. For a piece of movable snow (e.g., snowflake), the particles are connected using springs. Thus, we can model snow as a type of brittle material, such as a snow pile split into chunks of smaller snow pieces after a collision. To render the snow, we adopt a shell structure that has a series of concentric, semitransparent, textured shells. We applied our system to several examples, with the rendered snow appearing similar to real snow. Copyright © 2015 John Wiley &amp; Sons, Ltd.