Subarctic climate

The subarctic climate, also known as a boreal or subpolar climate, is a continental climate. It is defined by long, very cold winters and short summers. These summers can be warm or cool. This climate is usually found on large landmasses. It is often far from the moderating influence of an ocean. Most subarctic regions sit between 50°N and 70°N latitude. They are located poleward of humid continental climates.

This climate creates extreme seasonal temperature variations. In the winter, temperatures can drop very low. Record low temperatures can approach -60°C. In the summer, temperatures may exceed 30°C. To be classified as subarctic, at least one month must have a 24-hour average temperature of at least 10°C. The coldest month must average below 0°C. Because there are five to seven months of freezing temperatures, the ground freezes deeply. This creates permafrost, which is ground that stays frozen.

Scientists use the Köppen climate classification to group these regions. The first letter, D, indicates continentality. This means the coldest month is below 0°C. The second letter describes precipitation patterns. An 's' means the summer is dry. A 'w' means the winter is dry. An 'f' means there is no dry season. The third letter describes the temperature levels. A 'c' denotes regular subarctic conditions. A 'd' denotes a severely cold subarctic climate.

Precipitation levels vary depending on the location. Most subarctic climates have low precipitation. This is because of low temperatures and low evapotranspiration. Evapototranspiration is the process of water moving from the ground and plants into the air. Away from coasts, most precipitation falls in summer. In coastal areas, the heaviest precipitation often occurs in autumn. Some high-elevation areas are exceptions. For example, Mount Washington receives 1,100 mm of rain-equivalent precipitation per year. The Kamchatka peninsula and Sakhalin island are also very wet.

The vegetation in these regions is often called taiga. The taiga is the largest forest biome on Earth. Most of these forests are in Russia and Canada. Because of the cold, there is low plant diversity. Only hardy tree species can survive the long winters. Most trees are conifers, which are trees like pines. These trees use a process called hardening to prepare for the cold. Agriculture is generally difficult in these areas. The soil is often naturally infertile. Many areas are also covered in swamps and lakes.

Subarctic climates are found across many parts of the world. In Eurasia, they cover much of Siberia and northern European Russia. Notable cities include Yakutsk and Murmansk. In North America, they cover much of Canada and Alaska. Cities like Whitehorse and Yellowknife are in these zones. In the Southern Hemisphere, these climates are very rare. They only exist in isolated places like the Snowy Mountains of Australia. They also appear in the Andes mountains of South America.

These climates connect to other global systems. Subarctic regions are source regions for cold air. This cold air affects temperate latitudes to the south during winter. To the north, the climate turns into tundra. Tundra is a climate that is not suitable for trees. To the south, it transitions into humid continental climates. In some areas, it may become a cold semi-arid climate. This happens in China and Mongolia where precipitation is very low.