How does moisture content affect soil heat capacity ?
Half of the volume of most soils consists of pores that may contain either air or water, depending on the moisture content. Air has a negligible capacity to absorb heat compared to soil minerals and water. Water has twice the capacity to absorb heat compared to soil minerals. That means moisture content strongly influences the actual heat capacity 1 of a soil. Each substance has a characteristic heat capacity. Suppose a fixed quantity of heat is absorbed by a gram of soil minerals, causing the temperature of the soil minerals increases by 10 degrees. The temperature of one gram water absorbing the same amount of heat would increase only 5 degrees because the heat capacity of water is about twice that of soil minerals. Replacing air with water in soil pores means the temperature of moist soil will increase less than a dry soil when both absorb the same amount of heat.
