NUCLEATION AND GROWTH INTERACTION IN ADIABATICALLY LIFTING CLOUD PARCEL

The nucleation-growth interaction above the convective cloud base was studied theoretically. By backtracking the zone of near constant droplet number concentration immediately after the supersaturation maximum, considering the cloud condensation nucleus (CCN) activity spectrum and the Maxwellian droplet growth theory, an analytic solution was obtained. The solution agrees with that of Twomey in the functional relationship, but the maximum supersaturation and the droplet number concentration were slightly larger than those of Twomey's upper limit expression. Applying the new solution, the effect of the CCN activity spectrum on the droplet radius has been assessed. The analytic solutions reported by Squires and Fukuta, without consideration of the CCN spectrum, are shown to be partial or diagnostic solutions. The relationship among the diagnostic solutions, the real solutions, and the CCN spectrum, both for Maxwellian and diffusion-kinetic droplet growth systems, is explained graphically, and the numerical method of solving the latter system is shown.