Wet snow
Typical temperature for wet snow formation is between 0 °C and 3°C. Falling snow or ice particles melt, when they enter in to the warm (over 0 °C) zone of the atmosphere. Depending on the degree of melting rain, slush or wet snow is formed. In the wet snow formation there is only a little of melting involved and on the contrary in the freezing rain there is complete melting in the warmer zone. The accreted wet snow will actually freeze on the surface, when temperature falls below 0 °C after accretion event.
When comparing wet snow to dry snow accretion, the key difference is that wet snow has very high LWC values (liquid water content) Partially melted, high water containing snowflakes are sticking very effectively on the surface and on the top of each other. However the mechanical forces the snow are weak due to porous structure.
Wet snow, or sticky snow, readily bonds to all surfaces where dry snow does not readily bond. [2]
Density of wet snow is in a range of 300-600 kg/m3 and it is mainly composed of liquid water, ice granules and air pockets. The whole structure is connected together by the capillary forces. Wet snow accretion cause mainly problems for overhead lines and collapsed structures.
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References
- ↑ L. Makkonen & B. Wichura, Simulating wet snow loads on power line cables by a simple model, Cold Regions Science and Technology, vol. 61, no. 2–3, 2010, pp. 73–81.
- ↑ Charles C. Ryerson. April 2013. Icing Management for Coast Guard Assets. Cold Regions Research and Engineering Laboratory. ERDC/ C R R E L TR-13-7.
- ↑ ISO-12494, Atmospheric icing of structures, 2001, 56 p.
- ↑ M. Tomaszewski & B. Ruszczak, Analysis of frequency of occurrence of weather conditions favouring wet snow adhesion and accretion on overhead power lines in Poland, Cold Regions Science and Technology, vol. 85, 2013, pp. 102–108, .
- ↑ I. Baring-Gould, R. Cattin, M. Dustewitz, M. Hulkkonen, A. Krenn, T. Laakso, A. Lacroix, E. Peltola, G. Rönsten, L. Tallhaug, T. Wallenius, Wind Energy Projects in Cold Climates, IEA Wind 13.task, 2012 43 p. Available: https://www.ieawind.org/index_page_postings/June%207%20posts/task%2019% 20cold_climate_%20rp_approved05.12.pdf.
- ↑ M. Farzaneh, Atmospheric icing of power networks. Springer, London, United Kingdom, 2008, 381 p.
- ↑ Properties of icephobic surfaces in different icing conditions. Stenroos Christian. Master of Science Thesis. TAMPERE UNIVERSITY OF TECHNOLOGY. October 2015. Online.