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Atmospheric Icing is icing happening in the air, when water droplets freeze on objects. The water droplets can be in form of [[Mist]], [[Fog]], [[Cloud]] or rain. Sometimes also water vapour can cause icing directly without the presence of liquid water.
[[File:Icing9.png|thumb|394x394px|Classification of atmospheric icing. ]]
Atmospheric icing is the creation of ice from water vapor, supercooled droplets, or ice crystals originating in the atmosphere. <ref>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.</ref>


The ice is often classified as follows:
Atmospheric icing is a phenomenon of complexity and many affecting factors. Atmospheric icing can be either precipitation icing (liquid water falls on the surface and freezes on it) or in-cloud icing (icing that occurs in a cloud or for example in fog).
* [[Clear ice]]
* [[Hard Rime]] ice
* [[Soft Rime]] ice
* [[Frost]]


[[Freezing rain]] causes [[Clear ice]] or [[Hard Rime]] ice. Freezing [[Fog]], clouds or [[Mist]] cause [[Soft Rime]] and cold water vapour may cause [[Frost]].
Liquid water in droplets can be in form of drop, droplet, hail or snow flake. The significant factor in atmospheric icing is super cooling of the water droplets, which means that temperature of droplets in the clouds or air is subzero. Depending on the icing conditions ice will occur as glaze ice, rime ice or mixed ice. Glaze is clear, dense, and hard ice. Rime ice is white and less dense, and softer. Mixed ice is a combination of glaze and rime and has properties from both. The accreted ice type is defined by factors as temperature, icing type , wind speed, air humidity, precipitation and water phase, material properties (surface topography and chemistry), wetting behavior and surface temperature. <ref>Niklas Kandelin. 2021. ICING FACTORS AFFECTING RAILWAY TRAFFIC.  Master of Science Thesis. Tampere University. </ref> <ref>Farzaneh, M. (2008) Atmospheric Icing of Power Networks. 1st ed. 2008. [Online]. Dordrecht: Springer Netherlands.</ref> <ref>Ingvaldsen, K. (2017) Atmospheric icing in a changing climate: Impact of higher boundary temperatures on simulations of atmospheric ice accretion on structures during the 2015-2016 icing winter in West-Norway.</ref>
[[File:Meteorological parameters of atmospheric icing.png|thumb|520x520px|Meteorological parameters of atmospheric icing.]]
[[File:Windbuchencom.jpg|thumb|370x370px|The effect of atmospheric icing on a tree in the Black Forest of Germany.<ref>Richardfabi. Public domain. Wikipedia. Atmospheric icing.</ref>|left]]


The international ISO standard Atmospheric Icing on Structures (ISO, E 2017) is based on Makkonen icing model. The icing model calculates the amount of ice accumulated over a 1m high vertically oriented, freely rotating cylinder with a diameter of 3 cm. A threshold value of 10 g/h for the modelled icing intensity is often used (Hämäläinen and Niemelä 2017; Kjeller Vindteknikk 2020) to distinguish between icing and non-icing conditions. Production of a Numerical Icing Atlas for Finland
==References==
 
<references />
The equation 3.1 describes the rime ice rate [g/h] over the standard cylinder, taking into account also melting
 
<math>\frac{\mathrm{d} M}{\mathrm{d} t}=\alpha_1 \cdot \alpha_2 \cdot \alpha_3 \cdot \rho_{LW} \cdot A \cdot v -Q_m,</math>
 
where dM/dt is the rate of accretion [g/s], The collision (α1), sticking (α2 ) and accretion (α3) are unitless coefficients and they describe the interactions between the cylinder and cloud water droplets. The ρLW is the liquid water content [g/m3], A is the surface area of the cylinder [m2] and v is the wind speed [m/s]. Liquid water content, ρLW depends on cloud type. In clean air ρLW=0, and in different kinds of clouds it varies ρLW = [0.03-3.0] g/cm3. The only relevant cloud type in our case is fog, when ρLW = 0.06 g/cm3. Another
 
{{Cite journal| doi = 10.1016/S0169-8095(97)00056-2| issn = 0169-8095| volume = 46| issue = 1| pages = 131–142| last = Makkonen| first = Lasse| title = Modeling power line icing in freezing precipitation| journal = Atmospheric Research| accessdate = 2021-06-24| date = 1998-04-01| url = https://www.sciencedirect.com/science/article/pii/S0169809597000562}}
{{Cite journal| doi = 10.1002/met.1964| issn = 1469-8080| volume = 27| issue = 6| pages = –1964| last1 = Hämäläinen| first1 = Karoliina| last2 = Hirsikko| first2 = Anne| last3 = Leskinen| first3 = Ari| last4 = Komppula| first4 = Mika| last5 = O'Connor| first5 = Ewan J.| last6 = Niemelä| first6 = Sami| title = Evaluating atmospheric icing forecasts with ground-based ceilometer profiles| journal = Meteorological Applications| accessdate = 2021-08-05| date = 2020| url = https://rmets.onlinelibrary.wiley.com/doi/abs/10.1002/met.1964}}
{{Cite journal| doi = 10.1002/we.517| title = Production of the Finnish Wind Atlas| accessdate = 2021-08-09| url = https://onlinelibrary.wiley.com/doi/10.1002/we.517}}
{{Cite journal| doi = 10.1002/we.1998| issn = 1099-1824| volume = 20| issue = 1| pages = 171–189| last1 = Hämäläinen| first1 = Karoliina| last2 = Niemelä| first2 = Sami| title = Production of a Numerical Icing Atlas for Finland| journal = Wind Energy| accessdate = 2021-08-09| date = 2017| url = https://onlinelibrary.wiley.com/doi/abs/10.1002/we.1998}}
{{Cite journal| doi = 10.1098/rsta.2000.0690| volume = 358| issue = 1776| pages = 2913–2939| last1 = Poots| first1 = G.| last2 = Makkonen| first2 = Lasse| title = Models for the growth of rime, glaze, icicles and wet snow on structures| journal = Philosophical Transactions of the Royal Society of London. Series A: Mathematical, Physical and Engineering Sciences| accessdate = 2021-08-12| date = 2000-11-15| url = https://royalsocietypublishing.org/doi/10.1098/rsta.2000.0690}}
{{Cite journal| doi = 10.1175/JTECH-D-14-00151.1| issn = 0739-0572, 1520-0426| volume = 32| issue = 8| pages = 1447–1463| last1 = Gregow| first1 = E.| last2 = Bernstein| first2 = B.| last3 = Wittmeyer| first3 = I.| last4 = Hirvonen| first4 = J.| title = LAPS–LOWICE: A Real-Time System for the Assessment of Low-Level Icing Conditions and Their Effect on Wind Power| journal = Journal of Atmospheric and Oceanic Technology| accessdate = 2021-08-20| date = 2015-08-01| url = https://journals.ametsoc.org/view/journals/atot/32/8/jtech-d-14-00151_1.xml}}

Latest revision as of 13:38, 25 February 2022

Classification of atmospheric icing.

Atmospheric icing is the creation of ice from water vapor, supercooled droplets, or ice crystals originating in the atmosphere. [1]

Atmospheric icing is a phenomenon of complexity and many affecting factors. Atmospheric icing can be either precipitation icing (liquid water falls on the surface and freezes on it) or in-cloud icing (icing that occurs in a cloud or for example in fog).

Liquid water in droplets can be in form of drop, droplet, hail or snow flake. The significant factor in atmospheric icing is super cooling of the water droplets, which means that temperature of droplets in the clouds or air is subzero. Depending on the icing conditions ice will occur as glaze ice, rime ice or mixed ice. Glaze is clear, dense, and hard ice. Rime ice is white and less dense, and softer. Mixed ice is a combination of glaze and rime and has properties from both. The accreted ice type is defined by factors as temperature, icing type , wind speed, air humidity, precipitation and water phase, material properties (surface topography and chemistry), wetting behavior and surface temperature. [2] [3] [4]

Meteorological parameters of atmospheric icing.
The effect of atmospheric icing on a tree in the Black Forest of Germany.[5]

References

  1. ↑ 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.
  2. ↑ Niklas Kandelin. 2021. ICING FACTORS AFFECTING RAILWAY TRAFFIC. Master of Science Thesis. Tampere University.
  3. ↑ Farzaneh, M. (2008) Atmospheric Icing of Power Networks. 1st ed. 2008. [Online]. Dordrecht: Springer Netherlands.
  4. ↑ Ingvaldsen, K. (2017) Atmospheric icing in a changing climate: Impact of higher boundary temperatures on simulations of atmospheric ice accretion on structures during the 2015-2016 icing winter in West-Norway.
  5. ↑ Richardfabi. Public domain. Wikipedia. Atmospheric icing.
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