Subarctic climate

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Regions having a subarctic climate (also called boreal climate) are characterized by long, usually very cold winters, and short, cool to mild summers. It is found on large landmasses, away from the moderating effects of an ocean, generally at latitudes from 50° to 70°N poleward of the humid continental climates. These climates represent Koppen climate classification Dfc, Dwc, Dfd and Dwd.

This type of climate offers some of the most extreme seasonal temperature variations found on the planet: In winter, temperatures can drop to −40 °C (−40 °F) and in summer, the temperature may exceed +30 °C (86 °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. The subarctic climate is a subset of the continental climate. The subarctic climate is found in the following areas^{[citation needed]}:

• Europe, Asia, and Northern North America not in United States (with the exception of Alaska)
• Much of Siberia
• The Western Alps between 1600 and 2100 meters (5,249 and 6,890 feet), Eastern Alps between 1450 and 1800 meters (4,757 and 5,905 feet) - France, Switzerland, Germany, Italy and Austria.
• Much of northern Mongolia
• Much of northern China
• The northern half of Scandinavia (milder winters in coastal areas)
• Most of Alaska
• Much of Canada from about 50-55°N to the tree line, including:
  • Southern Labrador
  • Certain areas within Newfoundland interior and along its northern coast
  • Northern Quebec except for the far north
  • Far northern Ontario
  • The northern Prairie Provinces
  • Most of the Yukon
  • Most of the Northwest Territories

With 5-7 consecutive months where 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 large areas. Seasonal thaw penetrates from 2 to 14 ft (0.6 to 4 m), depending on latitude, aspect, and type of ground.^[1] Some northern areas with subarctic climates located near oceans (southern Alaska and the northern fringe of Europe), have milder winters and no permafrost, and are thus more suited for farming.

The frost-free season is very short, varying from about 45 to 100 days at most, and a freeze can occur during any month in many areas. Vegetation in a subarctic climate is generally of low diversity, as only hardy species can survive the long winters and make use of the short summers. Trees are mostly limited to ferns and evergreen conifers, 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, 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

Agricultural potential is generally poor, due to the natural infertility of soils 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.^[1]

Should one go poleward 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 tundra climate even less suitable for trees.

Precipitation

Most subarctic climates have very little precipitation, typically no more than 15 inches (38 cm) over an entire year. Away from the coasts, precipitation occurs mostly in the warmer months. Low precipitation, by the standards of more temperate regions with longer and warmer winters, is typically sufficient in view of the very low evapotranspiration to allow a water-sogged terrain in many areas of subarctic climate.

A notable exception to this pattern is that subarctic climates occurring at high-altitudes in otherwise temperate regions have extremely high precipitation due to orographic lift. Mount Washington, with temperatures typical of a subarctic climate, receives an average rain-equivalent of 101.91 inches of precipitation per year.^[2]

Locations with subarctic climates

Sample locations with such climates^[3]:

• Anchorage, USA
• Fairbanks, USA
• Whitehorse, Canada
• Yellowknife, Canada
• Thompson, Canada
• Moosonee, Canada
• Goose Bay, Canada
• Rovaniemi, Finland
• Kiruna, Sweden
• Luleå, Sweden
• Røros, Norway
• Hammerfest, Norway
• Murmansk, Russia
• Arkhangelsk, Russia
• Irkutsk, Russia
• Chita, Russia
• Livigno, Italy
• Saint Moritz, Switzerland
• Trepalle, Italy - some areas ET
• Samedan, Switzerland
• Santa Caterina di Valfurva, Italy

Sample locations with the extreme Dfd climate include:

• Oymyakon, Russia
• Verkhoyansk, Russia

Charts of Selected Cities

References