Geoscience Reference
In-Depth Information
Chapter 4
Factors of Cryosol Formation
4.1
Climate
4.1.1
Introduction
Other than the Aridisols in
Soil Taxonomy
(Soil Survey Staff
2010
), the cryosol
order is the only soil taxon in global and national systems that is based on climate.
The developers of ST pointed out that the Aridisols, Gelisols, and suborders (Cry-,
Gel-, Ud-, Ust-, Xer-) in most other orders are based on soil climate and not climate
per se
(Forbes
1986
). Because of their opposition to the use of
soil
climate as a
diagnostic soil property, developers of the WRB (IUSS WRB Working Group
2006
)
established the cryosol soil group based on the presence of a cryic horizon, “a
perennially frozen soil horizon in mineral or organic materials” (p. 17), i.e., perma-
frost. However, in ST, the control section, or solum, constitutes the active layer and
uppermost part of the transient layer and not the underlying permafrost (see Fig.
2.1
)
. In ST, permafrost is viewed as a parent material and not soil material.
Regardless of these differences in philosophy, there is little doubt that climate, or
soil climate, plays a critical, if not defi ning, role in the development of cryosols . In
this chapter, the climate of regions supporting cryosols is discussed including tem-
perature, precipitation and humidity, and wind—all of which are key to the develop-
ment of cryosols.
In the widely used Köppen system, two types of polar climate are distinguished,
ET, or tundra climate, and EF, or ice cap climate. However, this system does not
recognize the considerable variation in mean annual air temperature (MAAT) and
monthly temperatures in cryosol regions. French (
2007
) provided a useful classifi -
cation of polar and alpine climates (Table
4.1
). The scheme has fi ve periglacial cli-
mate types that differ on the basis of latitude, elevation, and diurnal and seasonal
patterns in air temperature, with the intensely cold, windy, and hyperarid Antarctic
continent being a sixth type.
