Geoscience Reference
In-Depth Information
annually. Some cryosol areas receive most of their precipitation during the summer
months as rain, such as Yakutask, Siberia; other areas, such as high mountains with
permafrost, receive most of their precipitation during the winter as snow.
The polar regions vary markedly in terms of the magnitude and seasonal vari-
ation in relative humidity. Areas close to the Arctic Ocean tend to be humid
(70-90 %). In contrast the dry valleys of Antarctica have a humidity of less than
20 %, especially during the winter months when katabatic winds pour off the
polar plateau. A major concern in the arctic is an apparent rise in humidity, which
is attributed to melting of sea ice and warming of the Arctic Ocean.
4.1.4
Wind
As with most of the climate parameters, there is considerable variation in diurnal,
seasonal, and mean annual wind velocities in areas with cryosols. In the Canadian
Arctic Archipelago, mean annual wind speeds range between 4 and 6 m s
−1
; in con-
trast, many alpine areas and continental Antarctica have exceptionally high wind
speeds. For example, the mean annual wind velocity on Mount Washington, New
Hampshire is 16 m s
−1
. Wind is normally considered an important soil-forming fac-
tor in alpine and Antarctic environments.
4.2
Biota
Although climate is the most important soil-forming factor in the cryosol region, the
biota resulting from climate, including plants and animals, are also important.
4.2.1
Vegetation
The circumarctic is commonly subdivided by latitude, permafrost continuity, and
vegetation into the subarctic, Low Arctic, Mid-Arctic, and High Arctic regions
(Fig.
4.1
). The subarctic or taiga contains primarily open boreal forest and is under-
lain by sporadic or isolated permafrost. The low arctic contains low forms of veg-
etation, primarily peaty and mineral graminoid tundra, and is underlain by
discontinuous permafrost. The mid-arctic also has tundra vegetation and is under-
lain by discontinuous permafrost. The high arctic or polar desert contains crypto-
gam, herb barrens and mountain complexes and prostrate and semi-prostrate
dwarf-shrub, herb tundra and is underlain by continuous permafrost. The vegeta-
tion types within each region are illustrated in Fig.
4.2
. About 26 % of the vege-
tated area is erect shrub land, 18 % peaty graminoid tundra, 13 % mountain
