Editing Alpine climate (section)

==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&nbsp;°C and 1.5&nbsp;°C (biotemperature can never be below 0&nbsp;°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|bibcode=1999JBiog..26.1025L |s2cid=11733879 }}</ref> Therefore, he defined biotemperature as the mean of all temperatures but with all temperatures below freezing and above 30&nbsp;°C adjusted to 0&nbsp;°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 |archive-url=https://web.archive.org/web/20170525074713/ftp://ftp.ncdc.noaa.gov/pub/data/normals/1981-2010/products/station/USW00014755.normals.txt |archive-date=2017-05-25 |url-status=dead |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 |archive-url=https://web.archive.org/web/20170525074713/ftp://ftp.atdd.noaa.gov/pub/GCOS/WMO-Normals/TABLES/REG_IV/US/GROUP3/72613.TXT |archive-date=2017-05-25 |url-status=dead |access-date=9 June 2014}}</ref>