Subarctic climate

The subarctic climate (also called subpolar climate, or boreal climate) is a continental 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 at latitudes from 50°N to 70°N, poleward of the humid continental climates. Subarctic or boreal climates are the source regions for the cold air that affects temperate latitudes to the south in winter. These climates represent Köppen climate classification Dfc, Dwc, Dsc, Dfd, Dwd and Dsd.

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 −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, so permafrost 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 (southern Alaska, the northern fringe of Europe, 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 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 than 1⁄3 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).

Precipitation

Most subarctic climates have little precipitation, typically no more than 380 mm (15 in) 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

Agricultural potential is generally poor, due to the natural infertility of soils[4] and the prevalence of swamps and lakes left by departing ice 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]

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 10 °C (50 °F), and the subarctic climate grades into a

The Dfc climate, by far the most common subarctic type, is found in the following areas:[5]^[6]

• Northern Eurasia
  • The majority of Siberia
  • The Kamchatka Peninsula and the northern and central parts of the Kuril Islands and Sakhalin Island
  • The northern half of Fennoscandia (milder winters in coastal areas) and higher elevations further south.
  • The Western Alps between 1,600 and 2,100 meters (5,249 and 6,890 ft), and the Eastern Alps between 1,450 and 1,800 meters (4,757 and 5,906 ft)
  • Central Romania
  • Some parts of central Germany
  • The Tatra Mountains in Poland and Slovakia, above 800 meters (2,625 ft).
  • The Pyrenees, between 1,600 and 2,100 meters (5,249 and 6,890 ft)
  • The
    Pontic Alps, between 1,600 and 2,100 meters (5,249 and 6,890 ft)^{[citation needed}
    ]
  • Mountain summits in
    Nevis Range^{[citation needed}
    ]
  • The far northeast of Turkey

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 creates Dfd climates, which are mostly found in the Sakha Republic:

• Northeast Siberian taiga
• Central Yakutian Lowland
• Yakutsk
• Oymyakon
• Verkhoyansk

• North America
  • Most of
    Interior, Western and Southcentral Alaska
  • The high
    White Mountains of New Hampshire
  • Much of Canada from about 53–55°N to the tree line, including:
    • Southern Labrador
    • Certain areas within Newfoundland interior and along its northern coast
    • Quebec: Jamésie, Côte-Nord and far southern Nunavik
    • Far northern Ontario
    • The northern
      Prairie Provinces
    • The Rocky Mountain Foothills in Alberta and British Columbia
    • Most of the Yukon
    • Most of the Northwest Territories
    • Southwestern Nunavut

In the

Climates classified as Dsc or Dsd, with a dry summer, are rare, occurring in very small areas at high elevation around the Mediterranean Basin, Iran, Kyrgyzstan, Tajikistan, Alaska and other parts of the northwestern United States (Eastern Washington, Eastern Oregon, Southern Idaho, California's Eastern Sierra), the Russian Far East, Seneca, Oregon, and Atlin, British Columbia. Turkey and Afghanistan are exceptions; Dsc climates are common in Northeast Anatolia, in the Taurus and Köroğlu Mountains, and the Central Afghan highlands.

In the Southern Hemisphere, some of the highest mountains of the Andes in Chile and Argentina have Dsc climates.

Dwc and Dwd distribution

Climates classified as Dwc or Dwd, with a dry winter, are found in parts of East Asia, like China, where the Siberian 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. The Dwc climate can be found in:

• Much of northern Mongolia
• Russia:
  • Most of Khabarovsk Krai except the south
  • Southeastern Sakha Republic
  • Southern Magadan Oblast
  • Northern Amur Oblast
  • Northern
    Buryatia
  • Zabaykalsky Krai
  • Irkutsk Oblast
• China:
  • Mohe County in Heilongjiang
  • Northern Hulunbuir in Inner Mongolia
  • Gannan in Gansu (due to extreme elevation)
  • Huangnan, eastern Hainan and eastern Guoluo in Qinghai (due to extreme elevation)
  • Most of Garzê and Ngawa Autonomous Prefectures (due to extreme elevation) in Sichuan
  • Most of
    Qamdo Prefecture (due to extreme elevation) in the Tibet Autonomous Region
• Parts of
  Spiti regions of India^{[citation needed}
  ]
• Middle reaches of the Himalayas in Nepal, Bhutan, Myanmar, and Northeast India.
• Parts of
  Musan) in North Korea^{[citation needed}
  ]

• Boreal ecology
• Köppen climate classification
• Subantarctic
• Taiga

References