Arctic Environment

The Arctic climate is characterized by short, cold summers and long, extremely cold winters. It has 24 h of daylight during much of the summer, and darkness during much of the winter. Mean daily temperatures above 0°C occur only during the warmest part of the summer. The range of mean July temperatures is 7-10°C in the southern part of the Arctic and 3-5°C in the northern part. The coldest month is February, with temperatures of -20 to -40°C. Total annual precipitation is generally low (60-160 mm) and occurs mostly as snow.

The Arctic vegetation is a nearly continuous cover of shrub-tundra in the south, grading to a sparse cover of dwarf shrubs, herbs, mosses and lichens in the north. Permafrost is continuous, and reaches a thickness of 100-500 m in North America and >500 m in Siberia. The active layer (the surface layer which freezes and thaws annually) is about 30-60 cm thick. The soil surface is generally associated with patterned ground, which refers to a land surface that displays an ordered and repeated, more-or-less symmetrical, morphological pattern. A number of patterned ground classification systems occur in the literature, but the one most commonly used was developed for mineral terrain by Washburn (1980). This classification uses descriptive terminology based on geometric forms and the presence or absence of sorting of stones (coarse) and finer materials. The patterned ground forms for mineral terrain are circles, nets, steps, stripes, and polygons.

0 0

Post a comment