Climate characterised by long, usually very cold winters, and short, cool summers
Subarctic climate worldwide
Dsc
Dsd
Dwc
Dwd
Dfc
Dfd
Thesubarctic climate (also calledsubpolar climate, orboreal climate) is acontinental climate with long, cold (often very cold) winters, and short, warm to cool summers. It is found on large landmasses, often away from the moderating effects of an ocean, generally atlatitudes from 50°N to 70°N, poleward of thehumid continental climates. Like other Class D climates, they are rare in the Southern Hemisphere, only found at some isolated highland elevations. Subarctic or boreal climates are the source regions for the cold air that affects temperate latitudes to the south in winter. These climates representKöppen climate classificationDfc,Dwc,Dsc,Dfd,Dwd andDsd.
This type of climate offers some of the most extreme seasonal temperature variations found on the planet: in winter, temperatures can drop to below −50 °C (−58 °F) and in summer, the temperature may exceed 26 °C (79 °F). 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 10 °C (50 °F) to fall into this category of climate, and the coldest month should average below 0 °C (32 °F) (or −3 °C (27 °F)). Record low temperatures can approach −70 °C (−94 °F).[1]
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, sopermafrost prevails under most areas not near the southern boundary of this climate zone. Seasonal thaw penetrates from 2 to 14 ft (0.6 to 4.3 m), depending on latitude, aspect, and type of ground.[2] Some northern areas with subarctic climates located near oceans (southernAlaska, northernNorway,Sakhalin Oblast andKamchatka 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.
The first D indicates continentality, with the coldest month below 0 °C (32 °F) (or −3 °C (27 °F)).
The second letter denotes precipitation patterns:
s: A dry summer—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 30 millimetres (1.18 in)/40 millimetres (1.57 in) of rainfall and has exactly or less than1⁄3 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—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—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 10 °C (50.0 °F), coldest month between 0 °C (32 °F) (or −3 °C (27 °F)) and −38 °C (−36.4 °F).
d: Severely cold subarctic, only one–three months above 10 °C (50.0 °F), coldest month at or below −38 °C (−36.4 °F).
Most subarctic climates have little precipitation, typically no more than 380 mm (15 in) over an entire year due to the low temperatures andevapotranspiration. 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 lowevapotranspiration 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 toorographic lift.Mount Washington, with temperatures typical of a subarctic climate, receives an average rain-equivalent of 101.91 inches (2,588.5 mm) of precipitation per year.[3] Coastal areas ofKhabarovsk Krai also have much higher precipitation in summer due to orographic influences (up to 175 millimetres (6.9 in) in July in some areas), whilst the mountainousKamchatka peninsula andSakhalin island are even wetter, since orographic moisture isn't confined to the warmer months and creates largeglaciers in Kamchatka.Labrador, in eastern Canada, is similarly wet throughout the year due to the semi-permanentIcelandic Low and can receive up to 1,300 millimetres (51 in) of rainfall equivalent per year, creating a snow cover of up to 1.5 metres (59 in) that does not melt until June.
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.Trees are mostly limited toconifers, as few broadleaved trees are able to survive the very low temperatures in winter. This type of forest is also known astaiga, 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 inRussia andCanada. The process by which plants become acclimated to cold temperatures is calledhardening.
Agricultural potential is generally poor, due to the natural infertility of soils[4] and the prevalence of swamps and lakes left by departingice sheets, 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.[2]
Should one go northward or even toward a polar sea, one finds that the warmest month has an average temperature of less than 10 °C (50 °F), and the subarctic climate grades into atundra climate not at all suitable for trees. Southward, this climate grades into thehumid continental climates with longer summers (and usually less-severe winters) allowingbroadleaf trees; in a few locations close to a temperate sea (as innorthern Norway andsouthern Alaska), this climate can grade into a short-summer version of anoceanic climate, thesubpolar 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 coldsemi-arid climate.
Further north and east in Siberia, continentality increases so much that winters can be exceptionally severe, averaging below −38 °C (−36 °F), even though the hottest month still averages more than 10 °C (50 °F). This createsDfd climates, which are mostly found in theSakha Republic:
In theSouthern Hemisphere, theDfc climate is found only in small, isolated pockets in theSnowy Mountains ofAustralia, theSouthern Alps ofNew Zealand, and theLesotho Highlands. InSouth America, this climate occurs on the western slope of the centralAndes inChile andArgentina, where climatic conditions are notably more humid compared to the eastern slope. The presence of the Andes mountain range contributes to a wetter climate on the western slope by capturing moisture from thePacific Ocean, resulting in increased precipitation, especially during the winter months. This climate zone supports the presence of temperate rainforests, mostly on highest areas of theValdivian rainforest in Chile and thesubantarctic forest in Argentina.
In the Southern Hemisphere, the Dsc climate is present inSouth America as a subarctic climate influenced by Mediterranean characteristics, often considered a high-altitude variant of the Mediterranean climate. It is located on the eastern slopes of the central ArgentineAndes and in some sections on the Chilean side. While there are no major settlements exhibiting this climate, several localities in the vicinity experience it, such asSan Carlos de Bariloche,Villa La Angostura,San Martín de los Andes,Balmaceda,Punta de Vacas, andTermas del Flaco.[7]
Climates classified asDwc orDwd, with a dry winter, are found in parts of East Asia, like China, where theSiberian High makes the winters colder than places like Scandinavia or Alaska interior but extremely dry (typically with around 5 millimeters (0.20 in) of rainfall equivalent per month), meaning that winter snow cover is very limited. TheDwc climate can be found in:
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