the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
| 07 Oct 2024
Snow Particle Motion in Process of Cornice Formation
Abstract. Snow cornices are a common snow pattern in cold regions, and their fracture and collapse can easily trigger avalanches. Despite numerous observations and experimental simulations on their formation process, the microscopic mechanism of their formation remains unclear. In this paper, based on wind-tunnel experiments and high-speed photography, experimental studies on the trajectory of particles surrounding the snow cornice were carried out. Results indicated that the cornice is composed of small-sized snow particles. Saltation is the most dominant moving pattern for particles adhering to cornice. Notably, particles at the edge exhibit lower impact velocities and a wider distribution of impact angles compared to those on the surface. Further analysis of force balance equations of particles at the edge explains the shape-forming mechanism of wedged-like snow cornice. This work enhances the understanding of the micro-mechanism of snow cornice formation, offering theoretical insights for avalanche prediction.
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CC1: 'Comment on egusphere-2024-2458', Bailiang Li, 14 Nov 2024
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This is a very timely study demonstrating the microscale snow particle motion associated with an understudied snow bedform "Cornice", which is believed closely related to snow avalanches. The methods used in this paper is sound, the experiment settings were carefully tuned, which leads trustworthy experiment results. However, I think there are some minor issues in this manuscript and hopefully the authors can address them during the revision.
- The title mentioned the cornice formation, however, the discussion is also related to cornice growth, Suggesting the title can change to Snow particle motion during cornice development
- It is great to identify the four major adhering patterns, but it will be nice to link the force analysis with these four patterns
- It will be nice to discuss the limitations of the study, e.g. wind speed, humidity and temperature impact on cornice development. The implications for this study should be also discussed, e.g. how this research help the understanding of the mechanisms of snow avalanches.
Citation: https://doi.org/10.5194/egusphere-2024-2458-CC1 -
AC1: 'Reply to CC1', Hongxiang Yu, 23 Nov 2024
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The comment was uploaded in the form of a supplement: https://egusphere.copernicus.org/preprints/2024/egusphere-2024-2458/egusphere-2024-2458-AC1-supplement.pdf
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RC1: 'Comment on egusphere-2024-2458', Anonymous Referee #1, 26 Nov 2024
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General comments
This paper presents a detailed observation of snow particle motion in order to understand the process of snow cornice formation. It also investigates the conditions under which snow particles adhere to snow cornices through particle-level force analysis. There are few cases where snow cornice formation has been observed, so even though this is a very small-scale experiment in a wind tunnel rather than a full-scale snow cornice, this study is very informative. In addition, it is expected that the detailed force analysis will lead to the construction of a model for the snow cornice formation process, making this work worthy of publication.Specific comments
There is a big question about the force analysis, which is the main topic of this paper. The wind tunnel experiment in this paper uses dendritic snow particles. Although it is not clearly stated in the paper, my personal experimental experience and personal communications with researchers suggest that snow cornices can only form when dendritic snow particles are used, whereas they do not grow when spherical particles are used. The reason for this is not entirely clear, but it is thought that the large contact surface of dendritic particles makes it easier for snow particles to adhere to each other than for spherical particles. However, this paper discusses the balance of forces assuming that the particles are spherical, so it is possible that the contribution of the contact area of dendritic snow particles is sought in other forces when considering adhesion. To make this paper fruitful, I recommend that the author re-examine whether there are differences in snow cornice formation and adhesion forces between spherical and dendritic particles. Of course, it may not be easy to discuss adhesion forces between dendritic particles, but I expect that the contribution of dendritic shapes can be estimated from the parts that cannot be explained by considering spherical particles.Technical corrections
Line 19: micr-mechanism -> micro-mechanism?Citation: https://doi.org/10.5194/egusphere-2024-2458-RC1 -
CC2: 'Comment on egusphere-2024-2458', Hongyi Li, 11 Dec 2024
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The study effectively addresses a critical gap in understanding the micro-mechanics of snow cornice formation and its role in avalanche initiation. Due to the limited research on cornices, this work stands out as a highlight. Using wind tunnel experiments and high-speed photography, it achieves precise and reproducible observations. Systematic analysis supports its conclusions with robust statistical and theoretical methods.
Specific suggestions:
1) While the wind tunnel experiments provide controlled conditions, they do not fully replicate natural environments with variable wind speeds, temperatures, and snow particle compositions. Including a brief discussion on these limitations and how they affect the results would enhance the study.
2) Discussing on how these findings could refine or enhance existing related or similar models would make the study more impactful.
Citation: https://doi.org/10.5194/egusphere-2024-2458-CC2
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