Editing Subarctic climate (section)

==Description==
This type of climate offers some of the most extreme seasonal temperature variations found on the planet: in winter, temperatures can drop to below {{convert|-50|°C}} and in summer, the temperature may exceed {{convert|26|°C}}. However, the summers are short; no more than three months of the year (but at least one month) must have a 24-hour average temperature of at least {{convert|10|°C}} to fall into this category of climate, and the coldest month should average below {{convert|0|°C}} (or {{convert|-3|°C}}). Record low temperatures can approach {{convert|-70|C}}.<ref>{{cite journal|last1=Stepanova|first1=N.A.|title=On the Lowest Temperatures on Earth|journal=Monthly Weather Review|volume=86|issue=1|pages=6–10|url=http://docs.lib.noaa.gov/rescue/mwr/086/mwr-086-01-0006.pdf|access-date=4 January 2018|bibcode=1958MWRv...86....6S|year=1958|doi=10.1175/1520-0493(1958)086<0006:OTLTOE>2.0.CO;2}}</ref>
 
With 5–7 consecutive months when the average temperature is below freezing, all moisture in the soil and subsoil freezes solidly to depths of many feet. Summer warmth is insufficient to thaw more than a few surface feet, so [[permafrost]] prevails under most areas not near the southern boundary of this climate zone. Seasonal thaw penetrates from {{convert|2|to|14|ft|m|1|abbr=on}}, depending on latitude, aspect, and type of ground.<ref name="usdf">[http://www.fs.fed.us/colorimagemap/images/130.html Subarctic Division] {{webarchive|url=https://web.archive.org/web/20100105072109/http://www.fs.fed.us/colorimagemap/images/130.html |date=2010-01-05 }}</ref> Some northern areas with subarctic climates located near oceans (southern [[Alaska]], northern [[Norway]], [[Sakhalin Oblast]] and [[Kamchatka Oblast]]), have milder winters and no permafrost, and are more suited for farming unless precipitation is excessive. The frost-free season is very short, varying from about 45 to 100 days at most, and a freeze can occur anytime outside the summer months in many areas.

===Description===
The first D indicates continentality, with the coldest month below {{convert|0|°C}} (or {{convert|-3|°C}}).

The second letter denotes precipitation patterns:
* ''s'': A dry summer&mdash;the driest month in the high-sun half of the year (April to September in the Northern Hemisphere, October to March in the Southern Hemisphere) has less than {{convert|30|mm|2|abbr=}}/{{convert|40|mm|2|abbr=}} of rainfall and has exactly or less than {{fraction|3}} the precipitation of the wettest month in the low-sun half of the year (October to March in the Northern Hemisphere, April to September in the Southern Hemisphere),
* ''w'': A dry winter&mdash;the driest month in the low-sun half of the year has exactly or less than one‑tenth of the precipitation found in the wettest month in the summer half of the year,
* ''f'': No dry season&mdash;does not meet either of the alternative specifications above; precipitation and humidity are often high year-round.

The third letter denotes temperature:
* ''c'': Regular subarctic, only one–three months above {{convert|10|°C|1}}, coldest month between {{convert|0|°C}} (or {{convert|-3|°C}}) and {{convert|-38|°C|1}}.
* ''d'': Severely cold subarctic, only one–three months above {{convert|10|°C|1}}, coldest month at or below {{convert|-38|°C|1}}.

===Precipitation===
Most subarctic climates have little precipitation, typically no more than {{convert|380|mm|abbr=on}} over an entire year due to the low temperatures and [[evapotranspiration]]. Away from the coasts, precipitation occurs mostly in the summer months, while in coastal areas with subarctic climates the heaviest precipitation is usually during the autumn months when the relative warmth of sea vis-à-vis land is greatest. Low precipitation, by the standards of more temperate regions with longer summers and warmer winters, is typically sufficient in view of the very low [[evapotranspiration]] to allow a water-logged terrain in many areas of subarctic climate and to permit snow cover during winter, which is generally persistent for an extended period.

A notable exception to this pattern is that subarctic climates occurring at high elevations in otherwise temperate regions have extremely high precipitation due to [[orographic lift]]. [[Mount Washington (New Hampshire)|Mount Washington]], with temperatures typical of a subarctic climate, receives an average rain-equivalent of {{convert|101.91|in|mm|1}} of precipitation per year.<ref>[http://www.mountwashington.org/weather/normals.php Mount Washington Observatory: Normals, Means, and Extremes, Retrieved July 1, 2009.]</ref> Coastal areas of [[Khabarovsk Krai]] also have much higher precipitation in summer due to orographic influences (up to {{convert|175|mm|in}} in July in some areas), whilst the mountainous [[Kamchatka]] peninsula and [[Sakhalin]] island are even wetter, since orographic moisture isn't confined to the warmer months and creates large [[glacier]]s in Kamchatka. [[Labrador]], in eastern Canada, is similarly wet throughout the year due to the semi-permanent [[Icelandic Low]] and can receive up to {{convert|1300|mm|in|0}} of rainfall equivalent per year, creating a snow cover of up to {{convert|1.5|m|in|0}} that does not melt until June.

===Vegetation and land use===
[[Vegetation]] in regions with subarctic climates is generally of low diversity, as only hardy tree species can survive the long winters and make use of the short summers. [[Tree]]s are mostly limited to [[Pinophyta|conifer]]s, as few broadleaved trees are able to survive the very low temperatures in winter. This type of forest is also known as [[taiga]], a term which is sometimes applied to the climate found therein as well. Even though the diversity may be low, the area and numbers are high, and the taiga (boreal) forest is the largest forest biome on the planet, with most of the forests located in [[Russia]] and [[Canada]]. The process by which plants become acclimated to cold temperatures is called [[Hardening (botany)|hardening]].

Agricultural potential is generally poor, due to the natural infertility of soils<ref>{{Cite web|url=https://www.fs.fed.us/land/ecosysmgmt/colorimagemap/images/130.html|title=Subarctic Division|website=www.fs.fed.us|access-date=2020-01-04}}</ref> and the prevalence of swamps and lakes left by departing [[ice sheet]]s, and short growing seasons prohibit all but the hardiest of crops. Despite the short season, the long summer days at such latitudes do permit some agriculture. In some areas, ice has scoured rock surfaces bare, entirely stripping off the overburden. Elsewhere, rock basins have been formed and stream courses dammed, creating countless lakes.<ref name="usdf" />

=== Neighboring regions ===
Should one go northward or even toward a polar sea, one finds that the warmest month has an average temperature of less than {{convert|10|°C}}, and the subarctic climate grades into a [[tundra climate]] not at all suitable for trees. Southward, this climate grades into the [[humid continental climate]]s with longer summers (and usually less-severe winters) allowing [[Broad-leaved tree|broadleaf trees]]; in a few locations close to a temperate sea (as in [[North Norway|northern Norway]] and [[Southcentral Alaska|southern Alaska]]), this climate can grade into a short-summer version of an [[oceanic climate]], the [[subpolar oceanic climate]], as the sea is approached where winter temperatures average near or above freezing despite maintaining the short, cool summers. In China and Mongolia, as one moves southwestwards or towards lower elevations, temperatures increase but precipitation is so low that the subarctic climate grades into a cold [[semi-arid climate]].