Atmospheric icing: Difference between revisions

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The effect of atmospheric icing on a tree in the Black Forest of Germany

Atmospheric icing occurs in the atmosphere when water droplets suspended in air freeze on objects they come in contact with. It is not the same as freezing rain, which is caused directly by precipitation.

Atmospheric icing also occurs on towers, wind turbines, boats, oil rigs, and trees. Unmanned aircraft are particularly sensitive to icing.^[1] In cold climates, particularly those at higher elevations, atmospheric icing is common in winter as elevated terrain interacts with supercooled clouds that can cause icing on contact.^[2] Ice loads are a major cause of catastrophic failures of overhead electrical power lines, as power lines can break under the sheer weight of accumulated ice. Therefore, estimation of maximum potential ice load is crucial in the structural design of power line systems to withstand ice loads,^[3] and this can be done with numerical icing models and examples that include meteorological data.^[4]

Formation

Water does not always freeze at 0 °C (32 °F). Water that persists in liquid state below this temperature is said to be supercooled, and supercooled water droplets cause icing on aircraft. Below −20 °C (−4 °F), icing is rare because clouds at these temperatures usually consist of ice particles rather than supercooled water droplets. Below −48 °C (−54 °F), supercooled water always freezes; therefore, icing is impossible.^[5]

In aviation

Icing conditions can be particularly dangerous to aircraft, as the built-up ice changes the aerodynamics of the flight surfaces and airframe and results in structural icing, which can increase the risk of a stall and potentially accidents.

There are three types of structural icing: rime icing, clear (or glaze) icing, and mixed icing. Rime ice is rough, milky, and opaque. It forms rapidly from small supercooled water droplets and is the most reported icing type. Colder temperatures, lower liquid water content, and small droplets favors the forming of rime icing. Clear ice is glossy, clear, or translucent. Compared to rime ice, clear ice forms relatively slowly and tends to appear with warmer temperatures, higher liquid water contents, and larger droplets. Mixed ice is a mixture of rime and clear ice.^[6]

The structural icing of an aircraft is largely determined by three factors: supercooled liquid water content, which decides how much water is available for icing; air temperature, with half of all reported icing occurring between −8 °C (18 °F) and −12 °C (10 °F); and droplet size, with small droplets influencing aircraft's leading edges and large droplets can impact further aft of the airfoil. Airspeed influence the icing too. In general, the faster the speed, the more ice accumulation. However, this is counteracted by airframe skin surface at higher airspeed, and as a result, structural icing is minimal when speed is above 575 kn (1,065 km/h; 662 mph). Additionally, the design of the aircraft will also influence the icing.^[6]

In stratiform clouds, icing is more mild. It generally form as rime or mixed icing and tends to be confined in a 3,000–4,000 ft (910–1,220 m) thick layer. In contrast, icing intensity level in cumuliform clouds may range from trace for small cumulus to severe for large ones in the form of clear or mixed icing in the upper levels and can extend to great heights.^[6]

To ensure flight safety, on-board ice protection systems have been developed on aircraft intended to fly through these conditions.

References

^ Hann, Richard; Johansen, Tor (2020). "Unsettled Topics in Unmanned Aerial Vehicle Icing (EPR2020008 Research Report) - SAE Mobilus". saemobilus.sae.org. doi:10.4271/epr2020008. hdl:11250/3113980. S2CID 226200723. Retrieved 2021-02-14.
^ Yang, Jing; Jones, Kathleen F.; Yu, Wei; Morris, Robert (2012-09-08). "Simulation of in-cloud icing events on Mount Washington with the GEM-LAM". Journal of Geophysical Research: Atmospheres. 117 (D17): n/a. Bibcode:2012JGRD..11717204Y. doi:10.1029/2012jd017520. ISSN 0148-0227.
^ Farzaneh, M. (2008) Atmospheric Icing of Power Networks. Springer Science & Business Media, 2008, 381 p. ISBN 978-1-4020-8530-7
^ Makkonen, L. (2000) Models for the growth of rime, glaze, icicles and wet snow deposits on structures. Philosophical Transactions of the Royal Society of London A, 358 (1776): 2913-2939.
^ Moore, Emily; Valeria Molinero (24 November 2011). "structural transformation in supercooled water controls the crystallization rate of ice". Nature. 479 (7374): 506–508. arXiv:1107.1622. Bibcode:2011Natur.479..506M. doi:10.1038/nature10586. PMID 22113691. S2CID 1784703.
^ ^a ^b ^c "Chapter 20: Icing". Aviation Weather Handbook (FAA-H-8083-28A ed.). Federal Aviation Administration. 2024. pp. 3–4.

Sources

FAA (U.S.) Advisory Circular 20-113: Pilot Precautions and Procedures to be taken in Preventing Aircraft Reciprocating Engine Induction System and Fuel System Icing Problems
FAA (U.S.) Advisory Circular 20-117: Hazards Following Ground Deicing and Ground Operations in Conditions Conducive to Aircraft Icing
FAA (U.S.) Advisory Circular 20-147: Turbojet, Turboprop, and Turbofan Engine Induction System Icing and Ice Ingestion
Wind Energy in Cold Climates: Icing on wind turbines

External links

[1] Hann, Richard; Johansen, Tor (2020). "Unsettled Topics in Unmanned Aerial Vehicle Icing (EPR2020008 Research Report) - SAE Mobilus". saemobilus.sae.org. doi:10.4271/epr2020008. hdl:11250/3113980. S2CID 226200723. Retrieved 2021-02-14.

[2] Yang, Jing; Jones, Kathleen F.; Yu, Wei; Morris, Robert (2012-09-08). "Simulation of in-cloud icing events on Mount Washington with the GEM-LAM". Journal of Geophysical Research: Atmospheres. 117 (D17): n/a. Bibcode:2012JGRD..11717204Y. doi:10.1029/2012jd017520. ISSN 0148-0227.

[3] Farzaneh, M. (2008) Atmospheric Icing of Power Networks. Springer Science & Business Media, 2008, 381 p. ISBN 978-1-4020-8530-7

[4] Makkonen, L. (2000) Models for the growth of rime, glaze, icicles and wet snow deposits on structures. Philosophical Transactions of the Royal Society of London A, 358 (1776): 2913-2939.

[5] Moore, Emily; Valeria Molinero (24 November 2011). "structural transformation in supercooled water controls the crystallization rate of ice". Nature. 479 (7374): 506–508. arXiv:1107.1622. Bibcode:2011Natur.479..506M. doi:10.1038/nature10586. PMID 22113691. S2CID 1784703.

[AWH-6] "Chapter 20: Icing". Aviation Weather Handbook (FAA-H-8083-28A ed.). Federal Aviation Administration. 2024. pp. 3–4.

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[2]

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[6]

@@ Line 1: / Line 1: @@
+{{Short description|Weather condition in which water droplets freeze onto objects they come in contact with}}
-[[Image:Windbuchencom.jpg|right|thumb|300px|The effect of atmospheric icing on a tree in the [[Black Forest]] of [[Germany]].]]
+[[Image:Windbuchencom.jpg|right|thumb|300px|The effect of atmospheric icing on a tree in the [[Black Forest]] of [[Germany]]]]
-'''Atmospheric icing''' occurs in the [[atmosphere]] when water droplets [[freezing|freeze]] on objects they come in contact with. [[Icing conditions]] can be particularly dangerous to [[aircraft]], as the built-up [[ice]] changes the [[aerodynamics]] of the flight surfaces, which can increase the risk of a [[Stall (fluid dynamics)|stall]]. For this reason, on-board [[ice protection system]]s have been developed, and aircraft are often [[deicing|deiced]] prior to take-off in icy environments.
+'''Atmospheric icing''' occurs in the [[atmosphere]] when water droplets suspended in air [[freezing|freeze]] on objects they come in contact with. It is not the same as [[freezing rain]], which is caused directly by precipitation.
-[[Water]] does not always freeze at {{convert|0|°C}}. Water that persists in liquid state below this temperature is said to be [[supercooled]], and supercooled water droplets cause icing on aircraft. Below {{convert|−20|°C}}, icing is rare because clouds at these temperatures usually consist of ice particles rather than supercooled water droplets.  Below {{convert|−48|°C}}, supercooled water cannot exist, therefore icing is impossible.<ref>{{cite journal|last=Moore|first=Emily|author2=Valeria Molinero |title=structural transformation in supercooled water controls the crystallization rate of ice|journal=Nature|date=24 November 2011|volume=479|pages=506–508|doi=10.1038/nature10586|arxiv = 1107.1622 |bibcode = 2011Natur.479..506M|pmid=22113691}}</ref>
-Icing also occurs on [[tower]]s, [[wind turbine]]s, [[boat]]s, [[Drilling rig|oil rigs]], trees and other objects exposed to low temperatures and water droplets. In cold climates on land, atmospheric icing can be common as elevated terrain interacts with cold clouds<ref>{{Cite journal|last=Yang|first=Jing|last2=Jones|first2=Kathleen F.|last3=Yu|first3=Wei|last4=Morris|first4=Robert|date=2012-09-08|title=Simulation of in-cloud icing events on Mount Washington with the GEM-LAM|url=https://agupubs.onlinelibrary.wiley.com/doi/abs/10.1029/2012JD017520|journal=Journal of Geophysical Research: Atmospheres|language=en|volume=117|issue=D17|pages=n/a–n/a|doi=10.1029/2012jd017520|issn=0148-0227}}</ref>. Ice loads are a major cause of catastrophic failures of overhead electric power lines. Their estimation is, therefore, crucial in the structural design of power line systems.<ref>Farzaneh, M. (2008) Atmospheric Icing of Power Networks. Springer Science & Business Media, 2008, 381 p. {{ISBN|978-1-4020-8530-7}}</ref> and can be done by numerical icing models that include meteorological data.<ref>Makkonen, L. (2000) Models for the growth of rime, glaze, icicles and wet snow deposits on structures. Philosophical Transactions of the Royal Society, London A, 358 (1776): 2913-2939.</ref>
+Atmospheric icing also occurs on [[tower]]s, [[wind turbine]]s, [[boat]]s, [[Drilling rig|oil rigs]], and trees. Unmanned aircraft are particularly sensitive to icing.<ref>{{Cite journal|title=Unsettled Topics in Unmanned Aerial Vehicle Icing (EPR2020008 Research Report) - SAE Mobilus|url=https://saemobilus.sae.org/content/EPR2020008/|access-date=2021-02-14|website=saemobilus.sae.org|year=2020|doi=10.4271/epr2020008|last1=Hann|first1=Richard|last2=Johansen|first2=Tor|s2cid=226200723 |hdl=11250/3113980|hdl-access=free}}</ref>  In cold climates, particularly those at higher elevations, atmospheric icing is common in winter as elevated terrain interacts with supercooled clouds that can cause icing on contact.<ref>{{Cite journal|last1=Yang|first1=Jing|last2=Jones|first2=Kathleen F.|last3=Yu|first3=Wei|last4=Morris|first4=Robert|date=2012-09-08|title=Simulation of in-cloud icing events on Mount Washington with the GEM-LAM|journal=Journal of Geophysical Research: Atmospheres|language=en|volume=117|issue=D17|pages=n/a|doi=10.1029/2012jd017520|bibcode=2012JGRD..11717204Y|issn=0148-0227|doi-access=free}}</ref> Ice loads are a major cause of catastrophic failures of overhead electrical power lines, as power lines can break under the sheer weight of accumulated ice. Therefore, estimation of maximum potential ice load is crucial in the structural design of power line systems to withstand ice loads,<ref>Farzaneh, M. (2008) Atmospheric Icing of Power Networks. Springer Science & Business Media, 2008, 381 p. {{ISBN|978-1-4020-8530-7}}</ref> and this can be done with numerical icing models and examples that include [[meteorology|meteorological data]].<ref>Makkonen, L. (2000) Models for the growth of rime, glaze, icicles and wet snow deposits on structures. Philosophical Transactions of the Royal Society of London A, 358 (1776): 2913-2939.</ref>
+== Formation ==
+[[Water]] does not always freeze at {{convert|0|°C}}. Water that persists in liquid state below this temperature is said to be [[supercooled]], and supercooled water droplets cause icing on aircraft. Below {{convert|−20|°C}}, icing is rare because clouds at these temperatures usually consist of ice particles rather than supercooled water droplets.  Below {{convert|−48|°C}}, supercooled water always freezes; therefore, icing is impossible.<ref>{{cite journal|last=Moore|first=Emily|author2=Valeria Molinero |title=structural transformation in supercooled water controls the crystallization rate of ice|journal=Nature|date=24 November 2011|volume=479|issue=7374|pages=506–508|doi=10.1038/nature10586|arxiv = 1107.1622 |bibcode = 2011Natur.479..506M|pmid=22113691|s2cid=1784703}}</ref>
+== In aviation ==
+{{main|Icing (aeronautics)}}
+[[File:Icing on a plane.jpg|thumb|Ice contamination as a result of encountering Supercooled Large Droplet (SLD) conditions]]
+[[Icing conditions]] can be particularly dangerous to [[aircraft]], as the built-up [[ice]] changes the [[aerodynamics]] of the flight surfaces and airframe and results in structural icing, which can increase the risk of a [[Stall (fluid dynamics)|stall]] and potentially accidents.
+There are three types of structural icing: rime icing, clear (or glaze) icing, and mixed icing. Rime ice is rough, milky, and opaque. It forms rapidly from small supercooled water droplets and is the most reported icing type. Colder temperatures, lower liquid water content, and small droplets favors the forming of rime icing. Clear ice is glossy, clear, or translucent. Compared to rime ice, clear ice forms relatively slowly and tends to appear with warmer temperatures, higher liquid water contents, and larger droplets. Mixed ice is a mixture of rime and clear ice.<ref name="AWH" />
+The structural icing of an aircraft is largely determined by three factors: supercooled liquid water content, which decides how much water is available for icing; air temperature, with half of all reported icing occurring between {{convert|-8|C}} and {{convert|-12|C}}; and droplet size, with small droplets influencing aircraft's leading edges and large droplets can impact further aft of the [[airfoil]]. Airspeed influence the icing too. In general, the faster the speed, the more ice accumulation. However, this is counteracted by airframe skin surface at higher airspeed, and as a result, structural icing is minimal when speed is above {{cvt|575|kn}}. Additionally, the [[Aircraft design process|design of the aircraft]] will also influence the icing.<ref name="AWH">{{cite AWH |year=2024 |chapter=20 |pages=3 — 4}}</ref>
+In [[stratiform|stratiform clouds]], icing is more mild. It generally form as rime or mixed icing and tends to be confined in a {{cvt|3000|-|4000|ft|adj=on}} thick layer. In contrast, icing intensity level in [[cumuliform|cumuliform clouds]] may range from trace for small cumulus to severe for large ones in the form of clear or mixed icing in the upper levels and can extend to great heights.<ref name="AWH" />
+To ensure flight safety, on-board [[ice protection system]]s have been developed on aircraft intended to fly through these conditions.
 ==See also==
@@ Line 13: / Line 30: @@
 * [[Soft rime]]
 * [[Icing (nautical)]]
-{{colend}}
+{{Div col end}}
 ==References==
 {{Reflist}}
 ;Sources
-* [http://www.airweb.faa.gov/Regulatory_and_Guidance_Library/rgAdvisoryCircular.nsf/0/F5BD7904E845409D862569AE00783347?OpenDocument FAA (U.S.) Advisory Circular 20-113]: Pilot Precautions and Procedures to be taken in Preventing Aircraft Reciprocating Engine Induction System and Fuel System Icing Problems
+* [https://web.archive.org/web/20070311160551/http://www.airweb.faa.gov/Regulatory_and_Guidance_Library/rgAdvisoryCircular.nsf/0/F5BD7904E845409D862569AE00783347?OpenDocument FAA (U.S.) Advisory Circular 20-113]: Pilot Precautions and Procedures to be taken in Preventing Aircraft Reciprocating Engine Induction System and Fuel System Icing Problems
-* [http://www.airweb.faa.gov/Regulatory_and_Guidance_Library/rgAdvisoryCircular.nsf/0/A6B4EB947B007B3C862569BD006871B5?OpenDocument FAA (U.S.) Advisory Circular 20-117]: Hazards Following Ground Deicing and Ground Operations in Conditions Conducive to Aircraft Icing
+* [https://web.archive.org/web/20070311160530/http://www.airweb.faa.gov/Regulatory_and_Guidance_Library/rgAdvisoryCircular.nsf/0/A6B4EB947B007B3C862569BD006871B5?OpenDocument FAA (U.S.) Advisory Circular 20-117]: Hazards Following Ground Deicing and Ground Operations in Conditions Conducive to Aircraft Icing
-* [http://www.airweb.faa.gov/Regulatory_and_Guidance_Library/rgAdvisoryCircular.nsf/0/9F369F487492E0CD86256E31006C881C?OpenDocument FAA (U.S.) Advisory Circular 20-147]: Turbojet, Turboprop, and Turbofan Engine Induction System Icing and Ice Ingestion
+* [https://web.archive.org/web/20070311160542/http://www.airweb.faa.gov/Regulatory_and_Guidance_Library/rgAdvisoryCircular.nsf/0/9F369F487492E0CD86256E31006C881C?OpenDocument FAA (U.S.) Advisory Circular 20-147]: Turbojet, Turboprop, and Turbofan Engine Induction System Icing and Ice Ingestion
 * [https://web.archive.org/web/20061202164732/http://virtual.vtt.fi/virtual/arcticwind/experience.htm Wind Energy in Cold Climates]: Icing on wind turbines
 ==External links==
-{{commons category|Atmospheric icing}}
+{{Commons category|Atmospheric icing}}
 *[https://www.wsj.com/articles/SB120753185285993925? Airline Regulators Grapple With Engine-Shutdown Peril] [[WSJ]] April 7, 2008
 *  [http://www-das.uwyo.edu/~geerts/cwx/notes/chap08/supercooled.html  Supercooled liquid water and airframe icing]
+{{Authority control}}
 [[Category:Precipitation]]