Du 1 8P Dtu p Px (2.4) Dt p ax Dv 1 8P Dv al (2.5) Dt p ay Dw 1 p Dt p + g T (2.6) Dt p z TR Bu av aw S+ a + 0 (2.7) ax ay az where u, v and w are the velocities in the x, y and z directions respectively, p is the density of air, P and T are the pressure and temperature deviations respectively from the neutral conditions, g is the acceleration due to gravity, and TR is the reference temperature. The basic hypothesis is that the above equations along with the assumption of the constancy of the heat and momentum fluxes describe the statistical characteristics of the turbulence in the ground layer completely. The characteristic parameters for the layer are then: g/TR, u* and q/C p where u, is the friction velocity. The only length and temperature scales that can be formed by a combination of these parameters are: 3 U* L = (2.8) T C P T = (2.9) Ku, Cp