1. The Global Distribution of Cold Environments Flashcards
- What are cold environments?
- What are the 3 main reasons why environments might be cold?
- Explain these 3 reasons.
- Cold environments are the icy landscapes that occur in high latitudes (around the poles) and high mountain areas (often referred to as Alpine regions). Such regions have severely cold temperatures, an abundance of snow and ice with little vegetation and, as they are difficult to exploit, they remain sparsely populated.
- High latitude - High altitude - Continentality (continental interiors)
- They’re at a high latitude. High latitudes are colder than lower latitudes because they recieve less solar radiation (the Sun’s energy hits the Earth at more of an angle at high latitudes so it’s spread over a larger area). - They’re at a high altitude. High altitudes are colder than lower altitudes because air temperature decreases with increasing altitude. Less of the Sun’s enery reflected back from the Earth is trapped at higher altitudes, making it colder. Lower air pressures higher up also mean temperatures drop. It gets between 6°C and 10°C colder for every 1000m you go up. - They’re in the middle of continents. The middle of continents are cold because they’re far away from the sea. In the summer, the land heats up quickly and the sea heats up slowly. In the winter, the land cools quickly and the sea cools slowly. So, in winter the sea warms the land near the coast, but not the interior. This effect is called continentality.
These factors control the distribution of the different types of cold environment - glacial, periglacial, alpine and polar.
Explain Glacial Environments.
Glacial environments are areas of land permanently covered by ice. The land can be covered by glaciers (e.g. the Fanz Josef, New Zealand) or ice sheets (e.g. the Greenland ice sheet). The largest of these is the continent of Antarctica and its surrounding ice shelves, which covers around 13 million km².
Glaciers and ice sheets only form where it’s really cold, so glacial environments are found:
- At high latitudes. E.g. the Antarctive Ice Sheet (in the southern hemisphere), and the Greenland Ice Sheet (in the northern hemisphere) are both entirely above 60° latitude.
- At high altitudes (regardless of the latitude). E.g. glaciers are found in the Himalayan mountains even thoigh they’re at a low latitude (around 30°). This is because it’s the highest mountain range in the world. Glaciers even form at latitudes close to the equator (e.g. the Antizana glacier in Ecuador).
Even though it can be really cold on low alititude land in the middle of continents, glaciers don’t form as there’s not enough snow.
Explain Periglacial (and tundra) Environments.
Periglacial (and tundra) environments are regions where the temperature is frequently or constantly below freezing, but not covered by ice. They contain a layer of permafrost (permanently frozen ground) on or below the surface. Vegetation is sparse in such areas.
They form where it’s persistenly below 0°c, so they’re found:
- At high latitudes. E.g. the northern parts of Asia, North America (such as Alaska) and Europe (such as Scandinavia) are all periglacial environments with large areas of permafrost.
- At high altitudes. Periglacial conditions exist around ice masses in mountain ranges. They’re also found on high altitude plateau areas, e.g. the Tibetan plateau in Asia, and the Bolivian plateau in South America.
- In Continental Interiors: In the interior of land masses. Periglacial conditions exist at lower latitudes and lower altitudes because of the effect of continentality, e.g. Siberia, central Asia.
Other such areas include northern Canada, and the islands of the Arctic Ocean such as Spitsbergen.
Explain Alpine Environments.
Alpine environments are cold regions of land at an altitude above the treeline. The treeline is the limit of the area that trees can grow in - above the treeline it’s too cold for trees to grow.
Alpine environments are always found at high altitudes. Alpine conditions can be found above the treeline on mountain ranges, e.g. in South Asia (the Himalayas, Karakoram, Tibet Plateau), in South America (Rockies, Cascades, Andes), and in Europe (Alps, Norwegian mountains). They can exist at any latitude, e.g. alpine conditions exist along much of the Rocky mountains in North America, which run north to south from above 50° to around 30° latitude.
Alpine environments may include periglacial and glacial conditions. Temperature decreases as altitude increases - permafrost (periglacial conditions) may exist above (and below) the treeline, permanent snow and ice (glacial conditions) may exist even higher up.
Explain Polar Environments.
There are two Polar Environments - one around the North Pole (the Arctic) and one around the South Pole (the Antarctic).
The Arctic:
The Arctic polar environment is cold because it exists at a high latitude.
The Arctic polar environment can be defined either by the Arctic circle (66°N) or by the 10°C July isotherm (areas north of this line have an average temperature below 10°C in July, the hottest month).
The area around the north pole is made up of sea ice (frozen sea water). The area of sea ice shrinks in the summer, leaving open sea, and refreezes in the winter.
Much of the Arctic polar environment is made up of the northern land areas of Asia, North America, and Europe. The land-based polar environment can include glacial environments, e.g. the Greenland Ice Sheet, and periglacial environments, e.g. northern Russia.
The Antarctic:
The Antarctic polar environment is cold because of it high latitude - the Antarctic circle (66°S latitude) doesn’t go all the way round the land mass of Antarctica though, so the polar environment around the south pole can be defined by the 10°C January isotherm (areas south of this line have an average temperature below 10°C in January, the hottest month).
Some of the Antarctic polar environment is also cold because it’s at a high altitude - the ice in some places is so thick it reaches an altitude of over 4000m.
The interior of Antarctica is also cold because of the effect of continentality - the centre is hundreds of kilometres from the warming effect of the oceans.
A large area around the Antarctic land mass is made up of sea ice. The area of sea ice changes throughout the year, shrinking in summer and refreezing in winter.
Most of the Antarctic polar region is on the huge land mass of Antarctica. The land-based polar environment includes glacial environments, e.g. the Antarctic Ice Sheet.
Cool fact: Antarctica is - 1.4 x bigger than the USA - 58 x bigger than the UK - 1.8 x bigger than Australia
