The fifth, sixth, and seventh are thermodynamic property groups. These properties or properties groups are independent of each other except that the difference in slope between the enthalpy h line and thermodynamic wet-bulb temperature T * line is small, and it is hard to determine their intersec- tion. Usually, atmospheric pressure pat is a known value based on the altitude of the location. Then, in the fifth property group, pws is a function of temperature T only. In the sixth property group, according to Eq. (2.33), a 1/v; that is, air density and moist volume are dependent on each other. In the seventh property group, for a given value of pat, properties w, pw , and Tdew are all dependent on each other.