Using the mathematical model to describe
heat and mass transfer in porous media,simulative comparisons on the
daily change of
soil temperature under different conditions for summer and winter,ambient wind velocity of 1m/s and 4m/s and
ambient relative humidity of 35% and 85% have been conducted respectively,.The numerical simulations show that: (1) Soil
Temperature at each point changes periodically with the periodical changes of ambient temperature and solar radiation. (2) The impact on soil temperature posed by ambient temperature and solar radiation decreases with the increasing of the depth from the soil surface,the daily change period of temperature turns long increasingly,which implies the effect of temperature hysteresises is distinct. (3) During the most part of a day in summer,soil temperatures in the upper
layer are higher than those in the deeper layer,whereas it is reversed in winter. (4) When wind speed is high,heat and mass transfer between the soil and the surroundings are enhanced,the higher the wind speed,the more the water evaporation,thereby the more heat is taken away from soil,which leads to a greater decrease of soil temperature,especially in the surface layer. (5) Due to the effect of water evaporation in dry climate,soil temperature at each point is lower than that of in humid climate.
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