Firn (/fɪərn/; from Swiss Germanfirn "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.
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
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.
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.
Referencesedit
^ abcvan 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.
^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.
^"DanielBruun Firn". Mapcarta. Retrieved 31 May 2019.
"Fundamentals of Physical Geography". physicalgeography.net.
Machguth, Horst; MacFerrin, Mike; van As, Dirk; Box, Jason E.; Charalampidis, Charalampos; Colgan, William; Fausto, Robert S.; Meijer, Harro A. J.; Mosley-Thompson, Ellen; van de Wal, Roderik S. W. (April 2016). "Greenland meltwater storage in firn limited by near-surface ice formation" (PDF). Nature Climate Change. 6 (4): 390–393. Bibcode:2016NatCC...6..390M. doi:10.1038/nclimate2899. hdl:1874/335472. S2CID 33914856.
"USGS Glossary of Selected Glacier and Related Terminology". ulcan.wr.usgs.gov.
January 10, 2024
firn, confused, with, fern, ɪər, from, swiss, german, firn, last, year, cognate, with, before, partially, compacted, névé, type, snow, that, been, left, over, from, past, seasons, been, recrystallized, into, substance, denser, than, névé, that, intermediate, s. Not to be confused with Fern Firn f ɪer n from Swiss German firn last year s cognate with before is partially compacted neve a type of snow that has been left over from past seasons and has been recrystallized into a substance denser than neve 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 Sampling the surface of a glacier There is increasingly dense firn between surface snow and blue glacier ice Firn field on the top of Sauleck Hohe TauernSnowflakes 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 editAntarctic Firn 1 4 Daniel Bruun Firn 5 Dreyer Firn 6 East Northwall Firn Rink Firn Sven Hedin Firn 7 West Northwall FirnOther uses editIn 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 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 Cuffey Kurt M Paterson W S B 3 May 2010 The Physics of Glaciers Fourth ed Elsevier ISBN 978 0123694614 LCCN 2009050362 page needed Hays Jeffrey GLACIERS TYPES MECHANICS DANGERS AND TERMS factsanddetails com Retrieved 2024 01 08 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 DanielBruun Firn Mapcarta Retrieved 31 May 2019 Dreyer Firn Mapcarta Retrieved 31 May 2019 Sven Hedin Firn Army Map Service United States Army Corps of Engineers Greenland 1 250 000Sources edit Firn Encyclopaedia Britannica Fundamentals of Physical Geography physicalgeography net Machguth Horst MacFerrin Mike van As Dirk Box Jason E Charalampidis Charalampos Colgan William Fausto Robert S Meijer Harro A J Mosley Thompson Ellen van de Wal Roderik S W April 2016 Greenland meltwater storage in firn limited by near surface ice formation PDF Nature Climate Change 6 4 390 393 Bibcode 2016NatCC 6 390M doi 10 1038 nclimate2899 hdl 1874 335472 S2CID 33914856 USGS Glossary of Selected Glacier and Related Terminology ulcan wr usgs gov Retrieved from https en wikipedia org w index php title Firn amp oldid 1194326737, wikipedia, wiki, book, books, library,
