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{{Short description|Partially compacted névé}}
{{distinguish|Fern}}
{{distinguish|Fern}}
__NOTOC__
[[File:Taku glacier firn ice sampling.png|thumb|right|Sampling the surface of a glacier. There is increasingly dense firn between surface snow and blue glacier ice.]]
[[File:Taku glacier firn ice sampling.png|thumb|right|Sampling the surface of a glacier. There is increasingly dense firn between surface snow and blue glacier ice.]]
[[File:Firn field on the top of Säuleck.jpg|thumb|right|Firn field on the top of [[Säuleck]], [[Hohe Tauern]]]]
[[File:Firn field on the top of Säuleck.jpg|thumb|right|Firn field on the top of [[Säuleck]], [[Hohe Tauern]]]]
'''Firn''' ({{IPAc-en|f|ɪər|n}}; from [[Swiss German]] {{lang|gsw|''firn''}} "last year's", cognate with ''before'') is partially compacted [[névé]], a type of [[snow]] that has been left over from past seasons and has been [[Recrystallization (chemistry)|recrystallized]] into a substance denser than névé. It is [[ice]] that is at an intermediate stage between snow and glacial ice. Firn has the appearance of wet sugar, but has a hardness that makes it extremely resistant to shovelling. Its density generally ranges from 0.4&nbsp;g/cm³ to 0.83&nbsp;g/cm³,<ref>Cuffey and Paterson (2010), The Physics of Glaciers 4th Edition</ref> and it can often be found underneath the snow that accumulates at the head of a [[glacier]].
'''Firn''' ({{IPAc-en|f|ɪər|n}}; from [[Swiss German]] {{lang|gsw|firn}} "last year's", cognate with ''before'') is partially compacted [[névé]], a type of [[snow]] that has been left over from past seasons and has been [[Recrystallization (chemistry)|recrystallized]] into a substance denser than névé. It is [[ice]] that is at an intermediate stage between snow and glacial ice.<ref name=Broeke/> Firn has the appearance of wet sugar, but has a hardness that makes it extremely resistant to shovelling. Its density generally ranges from 0.35&nbsp;g/cm<sup>3</sup> to 0.9&nbsp;g/cm<sup>3</sup>,<ref name=Broeke/><ref>{{cite book|last1=Cuffey|first1=Kurt M.|title=The Physics of Glaciers|last2=Paterson|first2=W. S. B.|publisher=Elsevier|isbn=978-0123694614|edition=Fourth|date=3 May 2010|lccn=2009050362|author-link2=Stan Paterson}}{{Page needed|date=March 2020}}</ref> and it can often be found underneath the snow that accumulates at the head of a [[glacier]].


[[Snowflake]]s are compressed under the weight of the overlying [[snowpack]]. Individual [[crystal]]s near the melting point are semiliquid and slick, allowing them to glide along other crystal planes and to fill in the spaces between them, increasing the ice's density. Where the crystals touch they bond together, squeezing the air between them to the surface or into bubbles.
[[Snowflake]]s are compressed under the weight of the overlying [[snowpack]]. Individual [[crystal]]s near the melting point are semiliquid and slick, allowing them to glide along other crystal planes and to fill in the spaces between them, increasing the ice's density. Where the crystals touch, they bond together, squeezing the air between them to the surface or into bubbles.


In the summer months, the crystal metamorphosis can occur more rapidly because of water percolation between the crystals. By summer's end, the result is firn.
In the summer months, the crystal metamorphosis can occur more rapidly because of water percolation between the crystals. By summer's end, the result is firn.<ref>{{Cite web |last=Hays |first=Jeffrey |title=GLACIERS: TYPES, MECHANICS, DANGERS AND TERMS |url=https://factsanddetails.com/world/cat51/sub323/item1314.html |access-date=2024-01-08 |website=factsanddetails.com |language=en}}</ref>


The minimum altitude that firn accumulates on a glacier is called the ''firn limit'', ''firn line'' or ''snowline''.
The minimum altitude that firn accumulates on a glacier is called the ''firn limit'', ''firn line'' or ''snowline''.

==List of firns==
*[[Antarctic Firn]]<ref name=Broeke>{{cite journal |last1=van den Broeke |first1=Michiel |title=Depth and Density of the Antarctic Firn Layer |journal=Arctic, Antarctic, and Alpine Research |date=1 May 2008 |volume=40 |issue=2 |pages=432–438 |doi=10.1657/1523-0430(07-021)[BROEKE]2.0.CO;2 |s2cid=198156588 |url=https://www.tandfonline.com/doi/full/10.1657/1523-0430%2807-021%29%5BBROEKE%5D2.0.CO%3B2 |issn=1523-0430}}</ref><ref>{{cite journal |last1=Veldhuijsen |first1=Sanne |last2=Van De Berg |first2=Willem Jan |last3=Brils |first3=Max |last4=Kuipers Munneke |first4=Peter |last5=van den Broeke |first5=Michiel |title=Contemporary Characteristics of the Antarctic Firn Layer (1979-2020) |journal=AGU Fall Meeting Abstracts |date=1 December 2021 |volume=2021 |pages=C35E–0919 |bibcode=2021AGUFM.C35E0919V |url=https://ui.adsabs.harvard.edu/abs/2021AGUFM.C35E0919V/abstract}}</ref>
*[[Daniel Bruun Firn]]<ref name="mapcarta1">{{cite web|url=https://mapcarta.com/19193824|title=DanielBruun Firn|work=Mapcarta|access-date=31 May 2019}}</ref>
*[[Dreyer Firn]]<ref name="mapcarta2">{{cite web|url=https://mapcarta.com/19193686|title=Dreyer Firn|work=Mapcarta|access-date=31 May 2019}}</ref>
*[[East Northwall Firn]]
*[[Rink Firn]]
*[[Sven Hedin Firn]]<ref>''Sven Hedin Firn'', [[Army Map Service]], [[United States Army Corps of Engineers]], Greenland 1:250,000</ref>
*[[West Northwall Firn]]


== Other uses ==
== Other uses ==
In colloquial and technical language, 'firn' is used to describe certain forms of [[Snow#By age|old snow or harsch]]:
In colloquial and technical language, "firn" is used to describe certain forms of [[Snow#Metamorphism|old snow]], including:
* Old snowfields or [[névé]] (''Firnfelder''), even if the snow is not yet one year old
* old [[Snow field|snowfields]], known as ''Firnfelder'' ({{Literal translation|firn fields}}), even if the snow is not yet one year old
* the more recent snow layers of a glacier (a 'firned' glacier)
* the more recent snow layers of a temperate, or "firned", [[glacier]]
* the uppermost, soft layer of snow that is frozen overnight and, as a result of spring sunshine and high air temperatures, forms on an area of old snow or ''[[harsch]]'' (a slope ''firns up''; in Switzerland called ''Sulz'', but this term in Germany refers to a certain depth at which skiing downhill is no longer enjoyable)
* used in skiing, the uppermost, soft layer of snow that is frozen overnight and, as a result of spring sunshine and high air temperatures, melts and reforms on an area of old snow or ''[[wiktionary:harsch|harsch]]'' ({{Literal translation|harsh}}, referring to the snow's rough texture)
As in the last context, a ski slope that experiences melting and refreezing into ''harsch'' is said to "firn up". In Switzerland, these slopes are called ''Sulz'', but in Germany, ''Sulz'' more often refers to a depth at which skiing downhill is no longer enjoyable.


== References ==
== References ==
{{Reflist}}
{{Reflist}}

⚫
* [http://vulcan.wr.usgs.gov/Glossary/Glaciers/glacier_terminology.html USGS Glossary of Selected Glacier and Related Terminology]
==Sources==
⚫
* [http://www.physicalgeography.net/fundamentals/10ae.html Fundamentals of Physical Geography]
* [http://www.britannica.com/EBchecked/topic/208027/firn Firn definition] on Encyclopædia Britannica
* {{cite web|url=http://www.britannica.com/EBchecked/topic/208027/firn |title=Firn |website= Encyclopædia Britannica}}
⚫
* {{cite web|url=http://www.physicalgeography.net/fundamentals/10ae.html |work=physicalgeography.net|title=Fundamentals of Physical Geography}}
*[http://www.nature.com/articles/nclimate2899.epdf?referrer_access_token=BzDiAKD2UFGCKubkBBZ0qNRgN0jAjWel9jnR3ZoTv0MNJ0fYlPx9C7NW9mMHwZr6HlBDJTdg_axT_FoO1SZzxZzoygkOjD6QVPlOgoX_JTtpvBUrzaVuEApxr5fKg690CtyeZZ83Vj3HsVJcyy0jDnvs-9qMi08WwIduQrV0vatc_yIIrOlD2zMi40QOooUFc1bbXMLfsvee8Ea-UeRm_YVI81WX8w2P1HioA-oz2oNhkrbJnBOqi4pBzWY_bzJ_aJ1jEHtL2J2rZdRRGQ3N0tgMjsq_nhmhfp_OPk10ljMmdfkaL9Ur3ijkMqLRZ7G0&tracking_referrer=www.washingtonpost.com]/Greenland Meltwater Storage in Firn Limited
*{{cite journal |last1=Machguth |first1=Horst |last2=MacFerrin |first2=Mike |last3=van As |first3=Dirk |last4=Box |first4=Jason E. |last5=Charalampidis |first5=Charalampos |last6=Colgan |first6=William |last7=Fausto |first7=Robert S. |last8=Meijer |first8=Harro A. J. |last9=Mosley-Thompson |first9=Ellen |last10=van de Wal |first10=Roderik S. W. |title=Greenland meltwater storage in firn limited by near-surface ice formation |journal=[[Nature Climate Change]] |date=April 2016 |volume=6 |issue=4 |pages=390–393 |doi=10.1038/nclimate2899 |bibcode=2016NatCC...6..390M |hdl=1874/335472 |s2cid=33914856 |url=https://backend.orbit.dtu.dk/ws/files/139555698/machguth_postprint.pdf }}
⚫
* {{cite web|website=ulcan.wr.usgs.gov|url=http://vulcan.wr.usgs.gov/Glossary/Glaciers/glacier_terminology.html |title=USGS Glossary of Selected Glacier and Related Terminology}}


{{Glaciers}}
{{Glaciers}}
{{Ice}}
{{Ice}}
{{Authority control}}


[[Category:Glaciology]]
[[Category:Glaciology]]
[[Category:Water ice]]
[[Category:Water ice]]
[[Category:Montane ecology]]
[[Category:Montane ecology]]
[[Category:Mountaineering]]
[[Category:Snow]]
[[Category:Snow]]

Latest revision as of 12:03, 8 January 2024

Not to be confused with Fern.
Sampling the surface of a glacier. There is increasingly dense firn between surface snow and blue glacier ice.
Firn field on the top of Säuleck, Hohe Tauern

Firn (/fɪərn/; from Swiss German firn "last year's", cognate with before) is partially compacted névé, a type of snow that has been left over from past seasons and has been recrystallized into a substance denser than névé. It is ice that is at an intermediate stage between snow and glacial ice.[1] Firn has the appearance of wet sugar, but has a hardness that makes it extremely resistant to shovelling. Its density generally ranges from 0.35 g/cm3 to 0.9 g/cm3,[1][2] and it can often be found underneath the snow that accumulates at the head of a glacier.

Snowflakes are compressed under the weight of the overlying snowpack. Individual crystals near the melting point are semiliquid and slick, allowing them to glide along other crystal planes and to fill in the spaces between them, increasing the ice's density. Where the crystals touch, they bond together, squeezing the air between them to the surface or into bubbles.

In the summer months, the crystal metamorphosis can occur more rapidly because of water percolation between the crystals. By summer's end, the result is firn.[3]

The minimum altitude that firn accumulates on a glacier is called the firn limit, firn line or snowline.

List of firns[edit]

Other uses[edit]

In colloquial and technical language, "firn" is used to describe certain forms of old snow, including:

  • old snowfields, known as Firnfelder (lit. 'firn fields'), even if the snow is not yet one year old
  • the more recent snow layers of a temperate, or "firned", glacier
  • used in skiing, the uppermost, soft layer of snow that is frozen overnight and, as a result of spring sunshine and high air temperatures, melts and reforms on an area of old snow or harsch (lit. 'harsh', referring to the snow's rough texture)

As in the last context, a ski slope that experiences melting and refreezing into harsch is said to "firn up". In Switzerland, these slopes are called Sulz, but in Germany, Sulz more often refers to a depth at which skiing downhill is no longer enjoyable.

References[edit]

  1. ^ a b c van den Broeke, Michiel (1 May 2008). "Depth and Density of the Antarctic Firn Layer". Arctic, Antarctic, and Alpine Research. 40 (2): 432–438. doi:10.1657/1523-0430(07-021)[BROEKE]2.0.CO;2. ISSN 1523-0430. S2CID 198156588.
  2. ^ Cuffey, Kurt M.; Paterson, W. S. B. (3 May 2010). The Physics of Glaciers (Fourth ed.). Elsevier. ISBN 978-0123694614. LCCN 2009050362.[page needed]
  3. ^ Hays, Jeffrey. "GLACIERS: TYPES, MECHANICS, DANGERS AND TERMS". factsanddetails.com. Retrieved 2024-01-08.
  4. ^ Veldhuijsen, Sanne; Van De Berg, Willem Jan; Brils, Max; Kuipers Munneke, Peter; van den Broeke, Michiel (1 December 2021). "Contemporary Characteristics of the Antarctic Firn Layer (1979-2020)". AGU Fall Meeting Abstracts. 2021: C35E–0919. Bibcode:2021AGUFM.C35E0919V.
  5. ^ "DanielBruun Firn". Mapcarta. Retrieved 31 May 2019.
  6. ^ "Dreyer Firn". Mapcarta. Retrieved 31 May 2019.
  7. ^ Sven Hedin Firn, Army Map Service, United States Army Corps of Engineers, Greenland 1:250,000

Sources[edit]

Retrieved from "https://en.wikipedia.org/w/index.php?title=Firn&oldid=1194326737"