Ajay Kumar at 17:02, 29 August 2023

2023-08-29T17:02:33Z

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{{Short description|Typical weather for regions above the tree line}}
{{For|the climate of the mountains named the "Alps"|Climate of the Alps}}
[[File:White Mountain CA.JPG|right|thumb|[[White Mountain Peak|White Mountain]], an alpine environment at {{convert|4300|m|ft|-3}} [[above sea level]] in [[California]]]]

'''Alpine climate''' is the typical [[weather]] ([[climate]]) for elevations above the [[tree line]], where trees fail to grow due to cold. This climate is also referred to as a '''mountain climate''' or '''highland climate'''.

==Definition==

There are multiple definitions of alpine climate.

In the [[Köppen climate classification]], the alpine and mountain climates are part of group ''E'', along with the [[polar climate]], where no month has a mean [[temperature]] higher than {{convert|10|C|F}}.<ref>{{cite book | last1=McKnight | first1=Tom L | last2=Hess | first2=Darrel | year=2000 | chapter=Climate Zones and Types: The Köppen System | title=Physical Geography: A Landscape Appreciation | pages=[https://archive.org/details/physicalgeographmckn/page/235 235–7] | location=Upper Saddle River, New Jersey | publisher=Prentice Hall | isbn=978-0-13-020263-5 | chapter-url-access=registration | chapter-url=https://archive.org/details/physicalgeographmckn | url=https://archive.org/details/physicalgeographmckn/page/235 }}</ref>

According to the [[Holdridge life zone]] system, there are two mountain climates which prevent tree growth :

a) the alpine climate,
which occurs when the mean [[biotemperature]] of a location is between {{convert|1.5|and|3|C|F}}. The alpine climate in Holdridge system is roughly equivalent to the warmest [[tundra]] climates (ET) in the Köppen system.

b) the alvar climate, the coldest mountain climate since the biotemperature is between 0 °C and 1.5 °C (biotemperature can never be below 0 °C). It corresponds more or less to the coldest tundra climates and to the [[ice cap climate]]s (EF) as well.

Holdrige reasoned that plants net primary productivity ceases with plants becoming dormant at temperatures below {{convert|0|C|F}} and above {{convert|30|C|F}}.<ref>{{cite journal|last1=Lugo|first1=A. E.|title=The Holdridge life zones of the conterminous United States in relation to ecosystem mapping|journal=Journal of Biogeography|date=1999|volume=26|issue=5|pages=1025–1038|url=https://www.researchgate.net/publication/227649905|access-date=27 May 2015|doi=10.1046/j.1365-2699.1999.00329.x|s2cid=11733879 }}</ref> Therefore, he defined biotemperature as the mean of all temperatures but with all temperatures below freezing and above 30 °C adjusted to 0 °C; that is, the sum of temperatures not adjusted is divided by the number of all temperatures (including both adjusted and non-adjusted ones).

The variability of the alpine climate throughout the year depends on the latitude of the location. For tropical oceanic locations, such as the summit of [[Mauna Loa]], the temperature is roughly constant throughout the year.<ref>{{cite web|work=MAUNA LOA SLOPE OBS, HAWAII|title=Period of Record Monthly Climate Summary|url=http://www.wrcc.dri.edu/cgi-bin/cliMAIN.pl?himaun|publisher=NOAA|access-date=2012-06-05}}</ref> For mid-latitude locations, such as [[Mount Washington (New Hampshire)|Mount Washington]] in [[New Hampshire]], the temperature varies seasonally, but never gets very warm.<ref name=NCDCtxt>{{cite web |title=Station Name: NH MT WASHINGTON |publisher=National Oceanic and Atmospheric Administration |url=ftp://ftp.ncdc.noaa.gov/pub/data/normals/1981-2010/products/station/USW00014755.normals.txt |access-date=9 June 2014}}</ref><ref name = NOAAsun >{{cite web |title=WMO Climate Normals for MOUNT WASHINGTON, NH 1961–1990 |publisher=National Oceanic and Atmospheric Administration |url=ftp://ftp.atdd.noaa.gov/pub/GCOS/WMO-Normals/TABLES/REG_IV/US/GROUP3/72613.TXT |access-date=9 June 2014}}</ref>

==Cause==
The temperature profile of the atmosphere is a result of an interaction between [[radiation]] and [[convection]]. Sunlight in the [[visible spectrum]] hits the ground and heats it. The ground then heats the air at the surface. If [[radiation]] were the only way to transfer heat from the ground to space, the [[greenhouse effect]] of gases in the atmosphere would keep the ground at roughly {{convert|333|K|C F}}, and the temperature would decay exponentially with height.<ref name=goodywilson>{{cite book|first1=Richard M.|last1=Goody|first2=James C.G.|last2=Walker|title=Atmospheres|chapter=Atmospheric Temperatures|chapter-url=http://lasp.colorado.edu/~bagenal/3720/GoodyWalker/AtmosCh3sm.pdf|publisher=Prentice-Hall|year=1972|access-date=2016-05-02|archive-date=2016-07-29|archive-url=https://web.archive.org/web/20160729075851/http://lasp.colorado.edu/~bagenal/3720/GoodyWalker/AtmosCh3sm.pdf|url-status=dead}}</ref>

However, when air is hot, it tends to expand, which lowers its density. Thus, hot air tends to rise and transfer heat upward. This is the process of [[convection]]. Convection comes to equilibrium when a parcel of air at a given altitude has the same density as its surroundings. Air is a poor conductor of heat, so a parcel of air will rise and fall without exchanging heat. This is known as an [[adiabatic process]], which has a characteristic pressure-temperature curve. As the pressure gets lower, the temperature decreases. The rate of decrease of temperature with elevation is known as the [[adiabatic lapse rate]], which is approximately 9.8 °C per kilometer (or 5.4 °F per 1000 feet) of altitude.<ref name=goodywilson/>

The presence of water in the atmosphere complicates the process of convection. Water vapor contains latent [[heat of vaporization]]. As air rises and cools, it eventually becomes [[Dew point|saturated]] and cannot hold its quantity of water vapor. The water vapor condenses (forming [[cloud]]s), and releases heat, which changes the lapse rate from the [[dry adiabatic lapse rate]] to the [[moist adiabatic lapse rate]] (5.5 °C per kilometre or 3 °F per 1000 feet).<ref>{{cite web|url=http://meteorologytraining.tpub.com/14312/css/14312_47.htm |title=Dry Adiabatic Lapse Rate |publisher=tpub.com |access-date=2016-05-02 |url-status=dead |archive-url=https://web.archive.org/web/20160603041448/http://meteorologytraining.tpub.com/14312/css/14312_47.htm |archive-date=2016-06-03 }}</ref> The actual lapse rate, called the [[environmental lapse rate]], is not constant (it can fluctuate throughout the day or seasonally and also regionally), but a normal lapse rate is 5.5 °C per 1,000 m (3.57 °F per 1,000 ft).<ref>{{cite book
| chapter-url=http://goldbook.iupac.org/A00144.html
| title=Adiabatic Lapse Rate
| work=Goldbook
| publisher=[[IUPAC]]| doi=10.1351/goldbook.A00144
| chapter=Adiabatic lapse rate in atmospheric chemistry
| year=2009
| isbn=978-0-9678550-9-7
}}</ref><ref>{{Cite book|last=Dommasch|first=Daniel O.|title=Airplane Aerodynamics (3rd ed.)|publisher=Pitman Publishing Co.|year=1961|page=22}}</ref> Therefore, moving up {{convert|100|m}} on a mountain is roughly equivalent to moving 80 kilometres (50 miles or 0.75° of [[latitude]]) towards the pole.<ref>{{cite journal
| title= Mountain Environments
| url= http://quin.unep-wcmc.org/mountains/mountain_watch/pdfs/mountainEnvironments.pdf
| archive-url= https://web.archive.org/web/20110825113735/http://quin.unep-wcmc.org/mountains/mountain_watch/pdfs/mountainEnvironments.pdf
| archive-date=2011-08-25
| publisher = United Nations Environment Programme World Conservation Monitoring Centre}}</ref> This relationship is only approximate, however, since local factors, such as proximity to [[ocean]]s, can drastically modify the climate.<ref>{{cite web
| url=http://www.ecn.ac.uk/Education/factors_affecting_climate.htm
| archive-url=https://web.archive.org/web/20110716163841/http://www.ecn.ac.uk/Education/factors_affecting_climate.htm
| archive-date=2011-07-16
| title=Factors affecting climate
| publisher=The United Kingdom Environmental Change Network}}</ref> As the altitude increases, the main form of [[precipitation (meteorology)|precipitation]] becomes [[snow]] and the [[wind]]s increase. The temperature continues to drop until the [[tropopause]], at {{convert|11000|m|ft}}, where it does not decrease further. This is higher than the highest [[summit]].

==Distribution==
Although this climate classification only covers a small portion of the Earth's surface, alpine climates are widely distributed. They are present in the [[Himalayas]], the [[Tibetan Plateau]], [[Gansu]], [[Qinghai]], the [[Alps]], the [[Pyrenees]], the [[Cantabrian Mountains]] and the [[Sierra Nevada (Spain)|Sierra Nevada]] in [[Eurasia]], the [[Andes]] in [[South America]], the [[Sierra Nevada (U.S.)|Sierra Nevada]], the [[Cascade Mountains]], the [[Rocky Mountains]], the northern [[Appalachian Mountains]] (Adirondacks and White Mountains), and the [[Trans-Mexican volcanic belt]] in [[North America]], the [[Southern Alps]] in [[New Zealand]], the [[Snowy Mountains]] in [[Australia]], high elevations in the [[Atlas Mountains]] and the [[Eastern Highlands]] of [[Africa]], and the central parts of [[Borneo]] and [[New Guinea]] and the summits of [[Mount Pico]] in the [[Atlantic]]<ref>{{cite web |title=Climate atlas of the archipelagos of the Canary Islands, Madeira and the Azores |url=https://www.ipma.pt/export/sites/ipma/bin/docs/publicacoes/atlas.clima.ilhas.iberico.2011.pdf |publisher=[[IPMA]], [[AEMET]] |access-date=17 June 2021}}</ref> and [[Mauna Loa]] in the [[Pacific]].

The lowest altitude of alpine climate varies dramatically by latitude. If alpine climate is defined by the tree line, then it occurs as low as {{convert|650|m|ft}} at 68°N in Sweden,<ref name=korner>{{cite journal|last1=Körner|first1=Ch|year=1998|title=A re-assessment of high elevation treeline positions and their explanation|journal=Oecologia|volume=115|pages=445–459|doi=10.1007/s004420050540|pmid=28308263|issue=4|url=http://culter.colorado.edu/~kittel/TreelineLat_Koerner98.pdf|bibcode=1998Oecol.115..445K|citeseerx=10.1.1.454.8501|s2cid=8647814|access-date=2015-08-05|archive-date=2006-09-11|archive-url=https://web.archive.org/web/20060911194023/http://culter.colorado.edu/%7ekittel/TreelineLat_Koerner98.pdf|url-status=dead}}</ref> while on [[Mount Kilimanjaro]] in Tanzania, the tree line is at {{convert|3950|m}}.<ref name=korner/>

==See also==
*[[Alpine plant]]
*[[Climate of the Alps]]
*[[List of alpine climate locations]]

==References==
{{Reflist|33em}}

{{Koppen}}
{{Authority control}}

{{DEFAULTSORT:Alpine Climate}}
[[Category:Alpine flora|*A]]
[[Category:Köppen climate types]]
[[Category:Mountain meteorology]]
[[Category:Montane ecology]]
[[Category:Climate by mountain range]]
[[Category:Climate of the Alps]]

Alpine climate - Revision history

Ajay Kumar at 17:02, 29 August 2023