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词条 Alpine climate
释义

  1. Definition

  2. Cause

  3. Distribution

  4. Monthly variability

  5. See also

  6. References

{{For|the climate of the mountains named the "Alps"|Climate of the Alps}}

Alpine climate is the average weather (climate) for the regions above the tree line. This climate is also referred to as a mountain climate or highland climate.

Definition

There are multiple definitions of alpine climate.

One simple definition is the climate which causes trees to fail to grow due to cold. According to the Holdridge life zone system, alpine climate occurs when the mean biotemperature of a location is between {{convert|1.5|and|3|C|F}}, which prevents tree growth. Biotemperature is defined as the mean temperature, except all temperatures below {{convert|0|C|F}} are treated as {{convert|0|C|F}}, because plants are dormant below freezing.[1]

In the Köppen climate classification, the alpine climate is part of "Group E", along with the polar climate, where no month has a mean temperature higher than {{convert|10|C|F}}.[2]

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.[3]

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.[3]

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 saturated and cannot hold its quantity of water vapor. The water vapor condenses (forming clouds), 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).[4] 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).[5][6] Therefore, moving up {{convert|100|m}} on a mountain is roughly equivalent to moving 80 kilometres (45 miles or 0.75° of latitude) towards the pole.[7] This relationship is only approximate, however, since local factors, such as proximity to oceans, can drastically modify the climate.[8] As the altitude increases, the main form of precipitation becomes snow and the winds 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. For example,

The Sierra Nevada, the Cascade Mountains, the Rocky Mountains, the Appalachian Mountains, and the summit of Mauna Loa in the United States, the Alps, the Trans-Mexican volcanic belt, the Snowy Mountains in Australia, the Pyrenees, Cantabrian Mountains and Sierra Nevada in Spain, the Andes, the Himalayas, the Tibetan Plateau, Gansu, and Qinghai in China, the Eastern Highlands of Africa, high elevations in the Atlas Mountains and the central parts of Borneo and New Guinea.

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,[9] while on Mount Kilimanjaro in Africa, the alpine climate and the tree line are met at {{convert|3950|m}}.[9]

Monthly variability

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, elev. {{convert|13679|ft|abbr=on}}, the temperature is roughly constant throughout the year:

{{Weather box
|location = Mauna Loa slope observatory (1961–1990)
|single line = Y
|Jan record high F = 67
|Feb record high F = 85
|Mar record high F = 65
|Apr record high F = 67
|May record high F = 68
|Jun record high F = 71
|Jul record high F = 70
|Aug record high F = 68
|Sep record high F = 67
|Oct record high F = 66
|Nov record high F = 65
|Dec record high F = 67
|year record high F = 85
|Jan high F = 49.8
|Feb high F = 49.6
|Mar high F = 50.2
|Apr high F = 51.8
|May high F = 53.9
|Jun high F = 57.2
|Jul high F = 56.4
|Aug high F = 56.3
|Sep high F = 55.8
|Oct high F = 54.7
|Nov high F = 52.6
|Dec high F = 50.6
|Jan low F = 33.3
|Feb low F = 32.9
|Mar low F = 33.2
|Apr low F = 34.6
|May low F = 36.6
|Jun low F = 39.4
|Jul low F = 38.8
|Aug low F = 38.9
|Sep low F = 38.5
|Oct low F = 37.8
|Nov low F = 36.2
|Dec low F = 34.3
|Jan record low F = 19
|Feb record low F = 18
|Mar record low F = 20
|Apr record low F = 24
|May record low F = 27
|Jun record low F = 28
|Jul record low F = 26
|Aug record low F = 28
|Sep record low F = 29
|Oct record low F = 27
|Nov record low F = 25
|Dec record low F = 22
|year record low F = 18
|precipitation colour=green
|Jan precipitation inch = 2.3
|Feb precipitation inch = 1.5
|Mar precipitation inch = 1.7
|Apr precipitation inch = 1.3
|May precipitation inch = 1.0
|Jun precipitation inch = 0.5
|Jul precipitation inch = 1.1
|Aug precipitation inch = 1.5
|Sep precipitation inch = 1.3
|Oct precipitation inch = 1.1
|Nov precipitation inch = 1.7
|Dec precipitation inch = 2.0
|Jan precipitation days = 4
|Feb precipitation days = 5
|Mar precipitation days = 6
|Apr precipitation days = 5
|May precipitation days = 4
|Jun precipitation days = 3
|Jul precipitation days = 4
|Aug precipitation days = 5
|Sep precipitation days = 5
|Oct precipitation days = 5
|Nov precipitation days = 5
|Dec precipitation days = 4
|unit precipitation days = 0.01 inch
|Jan snow inch = 0.0
|Feb snow inch = 1.0
|Mar snow inch = 0.3
|Apr snow inch = 1.3
|May snow inch = 0.0
|Jun snow inch = 0.0
|Jul snow inch = 0.0
|Aug snow inch = 0.0
|Sep snow inch = 0.0
|Oct snow inch = 0.0
|Nov snow inch = 0.0
|Dec snow inch = 1.0
|source = NOAA[10]}}

For mid-latitude locations, such as Mount Washington the temperature varies, but never gets very warm:

{{Weather box
|location = Mount Washington, elev. {{convert|1910.2|m|abbr=on|order=flip}} near the summit
|single line = Y
|Jan high F = 13.6
|Feb high F = 14.7
|Mar high F = 20.7
|Apr high F = 30.4
|May high F = 41.3
|Jun high F = 50.4
|Jul high F = 54.1
|Aug high F = 53.3
|Sep high F = 47.1
|Oct high F = 36.4
|Nov high F = 28.1
|Dec high F = 18.4
|year high F =34.0
|Jan mean F=4.8
|Feb mean F=6.2
|Mar mean F=12.9
|Apr mean F=23.9
|May mean F=35.6
|Jun mean F=45.0
|Jul mean F=49.1
|Aug mean F=48.2
|Sep mean F=41.6
|Oct mean F=30.2
|Nov mean F=20.7
|Dec mean F=10.1
|year mean F=
|Jan low F = −4.1
|Feb low F = −2.4
|Mar low F = 5.0
|Apr low F = 17.4
|May low F = 29.8
|Jun low F = 39.5
|Jul low F = 44.0
|Aug low F = 43.0
|Sep low F = 36.1
|Oct low F = 24.0
|Nov low F = 13.3
|Dec low F = 1.7
|year low F =20.6
|Jan record high F = 48
|Feb record high F = 43
|Mar record high F = 54
|Apr record high F = 60
|May record high F = 66
|Jun record high F = 72
|Jul record high F = 71
|Aug record high F = 72
|Sep record high F = 69
|Oct record high F = 62
|Nov record high F = 52
|Dec record high F = 47
|year record high F =72
|Jan record low F = −47
|Feb record low F = −46
|Mar record low F = −38
|Apr record low F = −20
|May record low F = −2
|Jun record low F = 8
|Jul record low F = 24
|Aug record low F = 20
|Sep record low F = 9
|Oct record low F = −5
|Nov record low F = −20
|Dec record low F = −46
|year record low F= −47
|precipitation colour = green
|Jan precipitation inch = 6.44
|Feb precipitation inch = 6.77
|Mar precipitation inch = 7.67
|Apr precipitation inch = 7.44
|May precipitation inch = 8.18
|Jun precipitation inch = 8.40
|Jul precipitation inch = 8.77
|Aug precipitation inch = 8.32
|Sep precipitation inch = 8.03
|Oct precipitation inch = 9.27
|Nov precipitation inch = 9.85
|Dec precipitation inch = 7.73
|year precipitation inch=96.87
|snow colour = green
|Jan snow inch = 44.0
|Feb snow inch = 40.1
|Mar snow inch = 45.1
|Apr snow inch = 35.6
|May snow inch = 12.2
|Jun snow inch = 1.0
|Jul snow inch = 0.0
|Aug snow inch = 0.1
|Sep snow inch = 2.2
|Oct snow inch = 17.6
|Nov snow inch = 37.8
|Dec snow inch = 45.5
|year snow inch=281.2
|unit precipitation days = 0.01 in
|unit snow days = 0.1 in
|Jan precipitation days = 19.7
|Feb precipitation days = 17.9
|Mar precipitation days = 19.0
|Apr precipitation days = 17.4
|May precipitation days = 17.4
|Jun precipitation days = 16.8
|Jul precipitation days = 16.5
|Aug precipitation days = 15.2
|Sep precipitation days = 13.9
|Oct precipitation days = 16.8
|Nov precipitation days = 19.1
|Dec precipitation days = 20.7
|year precipitation days=210.4
|Jan snow days = 19.3
|Feb snow days = 17.3
|Mar snow days = 16.6
|Apr snow days = 13.1
|May snow days = 6.4
|Jun snow days = 0.9
|Jul snow days = 0.1
|Aug snow days = 0.2
|Sep snow days = 1.7
|Oct snow days = 9.1
|Nov snow days = 14.6
|Dec snow days = 19.2
|year snow days=118.5
|Jan sun = 92.0 |Jan percentsun = 32
|Feb sun = 106.9 |Feb percentsun = 36
|Mar sun = 127.6 |Mar percentsun = 34
|Apr sun = 143.2 |Apr percentsun = 35
|May sun = 171.3 |May percentsun = 37
|Jun sun = 151.3 |Jun percentsun = 33
|Jul sun = 145.0 |Jul percentsun = 31
|Aug sun = 130.5 |Aug percentsun = 30
|Sep sun = 127.2 |Sep percentsun = 34
|Oct sun = 127.1 |Oct percentsun = 37
|Nov sun = 82.4 |Nov percentsun = 29
|Dec sun = 83.1 |Dec percentsun = 30
|year sun=1487.6 |year percentsun =33
|source = NOAA (normals 1981–2010, sun 1961–1990)[11][12][13]
|source 2 = extremes 1933–present[14][15]
}}

See also

  • Alpine plant
  • Climate of the Alps

References

1. ^{{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|accessdate=27 May 2015|doi=10.1046/j.1365-2699.1999.00329.x}}
2. ^{{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=235–7 | location=Upper Saddle River, New Jersey | publisher=Prentice Hall | isbn=978-0-13-020263-5}}
3. ^1 {{cite book|first1=Richard M.|last1=Goody|first2=James C.G.|last2=Walker|title=Atmospheres|chapter=Atmospheric Temperatures|chapterurl=http://lasp.colorado.edu/~bagenal/3720/GoodyWalker/AtmosCh3sm.pdf|publisher=Prentice-Hall|year=1972}}
4. ^{{cite web|url=http://meteorologytraining.tpub.com/14312/css/14312_47.htm |title=Dry Adiabatic Lapse Rate |publisher=tpub.com |accessdate=2016-05-02 |deadurl=yes |archiveurl=https://web.archive.org/web/20160603041448/http://meteorologytraining.tpub.com/14312/css/14312_47.htm |archivedate=2016-06-03 |df= }}
5. ^{{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 }}
6. ^{{Cite book|last=Dommasch|first=Daniel O.|title=Airplane Aerodynamics (3rd ed.)|publisher=Pitman Publishing Co.|year=1961|page=22}}
7. ^{{cite journal | title= Mountain Environments | url= http://quin.unep-wcmc.org/mountains/mountain_watch/pdfs/mountainEnvironments.pdf | archiveurl= https://web.archive.org/web/20110825113735/http://quin.unep-wcmc.org/mountains/mountain_watch/pdfs/mountainEnvironments.pdf | archivedate=2011-08-25 | publisher = United Nations Environment Programme World Conservation Monitoring Centre}}
8. ^{{cite web | url=http://www.ecn.ac.uk/Education/factors_affecting_climate.htm | archiveurl=https://web.archive.org/web/20110716163841/http://www.ecn.ac.uk/Education/factors_affecting_climate.htm | archivedate=2011-07-16 | title=Factors affecting climate | publisher=The United Kingdom Environmental Change Network}}
9. ^1 {{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}}
10. ^{{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|accessdate=2012-06-05}}
11. ^{{cite web| url = http://www.nws.noaa.gov/climate/xmacis.php?wfo=gyx| title = NOWData – NOAA Online Weather Data| publisher = National Oceanic and Atmospheric Administration| accessdate = June 19, 2013}}
12. ^{{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 |accessdate=9 June 2014}}
13. ^{{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 |accessdate=9 June 2014}}
14. ^{{cite web |title=Mount Washington Observatory: Normals, Means and Extreme |publisher=Mount Washington Observatory |url=http://www.mountwashington.org/weather/normals.php |accessdate=7 August 2010}}
15. ^{{cite web|date=14 January 2013 |title=Today's Weather atop Mount Washington |publisher=Mount Washington Observatory |url=http://www.mountwashington.org/weather/summit.php |archiveurl=https://www.webcitation.org/6Df8SgIz3?url=http://www.mountwashington.org/weather/summit.php |archivedate=14 January 2013 |deadurl=yes |df= }}
{{Koppen}}{{DEFAULTSORT:Alpine Climate}}

13 : Alpine flora|Climate|Climate of Africa|Climate of Asia|Climate of Australia|Climate of Europe|Climate of North America|Climate of South America|Köppen climate classifications|Mountain meteorology|Montane ecology|Climate by mountain range|Climate of the Alps
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