Periglacial climates Flashcards
Define the term periglacial?
Periglacial is a term meaning literally ‘around the ice’. The definition has been widened to refer to non-glacial, cold-climate processes and landforms ranging from high-latitude polar regions to high-altitude areas in mid an low latitudes.
Which processes dominate in periglacial environments?
In periglacial environments, frost processes dominate and permafrost occurs, although water and wind action may be active too.
What percentage of the Earth’s land surface do periglacial environments cover?
20%
State the four types of periglacial climate?
- Polar lowlands
- Sub-polar lowlands
- Mid-latitude lowlands
- Highlands
Describe polar lowlands?
- Mean temperature of coldest month is less than -3 degrees celsius
- Characterised by ice caps
- Bare rock surfaces and tundra vegetation
Describe sub-polar lowlands?
- Mean temperature of coldest month is less than -3 degrees celsius
- Mean temperature in the warmest month is more than 10 degrees celsius
- Taiga type of vegetation
Describe mid-altitude lowlands?
- Mean temperature of the coldest month is less than -3 degrees celsius
- Mean temperature is more than 10 degrees celsius for at least four months per year
Describe highlands?
- The climate is influenced by altitude as well as latitude
- Considerable variability over short distance depending on slope aspect
- Diurnal temperature ranges tend to be large
Give some of the characteristics of perigacial climates in general?
Periglacial climates are in general characterised by long, cold winters during which temperatures rarely rise above 0 degrees celsius (daily temperatures are below 0 degrees for at least nine months and below -10 degrees for at least 6 months). They are also characterised by a low mean annual precipitation of less than 1,000 mm.
To what extent do periglacial climates vary in the summer?
Although the length and average temperature of the summer can vary, temperatures need to be high enough to allow ice to melt because repeated freezing and tawing over long periods of time are essential for the operation of periglacial processes and the development of associated landforms.
Why are local conditions important in periglacial climates?
Local conditions are important. For instance, microclimate (due, for example, to variations in slope orientation and exposure) and the character of the ground surface and vegetation are important influences on the intensity and frequency of the freeze-thaw cycle.
