Summary: | Comparison of the temperatures at 50 cm depth in Fox Lake, Yukon Territory, with those at 10 cm depth in the soil on an adjacent lithalsa indicates that water absorbs between five and seven times as much solar energy as the soil on an annual basis. This is partly due to the differences in thermal properties between ice, water, soil and rock, but is also due to the water being translucent, and absorbing solar energy through a much thicker layer. Movements of water also help in the process. In winter, the soil cools down to −16°C whereas the lake ice remains warmer than −3°C. This is the reason that a thaw pond, once formed, will go on enlarging in icy materials until it runs out of ground ice or intersects a drainage way. Since thermokarst can be initiated by a variety of different agencies, a single occurrence cannot be used as a proof of climatic change. Copyright © 2002 John Wiley & Sons, Ltd.
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