Submitted to: Encyclopedia of Water Science
Publication Type: Book / Chapter
Publication Acceptance Date: November 20, 2001
Publication Date: N/A
Technical Abstract: Soil water freezes differently than pure water due to the effect of capillary and adsorptive forces that cause it to freeze incrementally over a range of temperatures. This behavior conforms with the Clapeyron equation, which describes the conditions for phase equilibrium, and is graphically represented in a freezing characteristic curve, that is analogous to the more commonly known moisture characteristic curve. The drop in water potential that accompanies freezing induces water movement toward the point of freezing. If the rate of heat loss is matched by the rate of water movement to the freezing front, then the pore space will fill with ice. This reduces the infiltration capacity of the soil, which can lead to problems associated with runoff and flooding when snow melts.