The effects of giant cloud condensation nuclei on the development of precipitation in convective clouds - a numerical study

Numerical experiments are conducted to investigate the effects of giant cloud condensation nuclei (CCN) on the development of precipitation in mixed-phase convective clouds. The results show that the strongest effects of introducing giant CCN occur when the background concentration of small nuclei is high, as that in continental clouds. Under these conditions, the coalescence between water drops is enhanced due to the inclusion of giant CCN, resulting in an early development of large drops at the lower parts of the clouds. It also leads to the formation of larger graupel particles and to more intensive radar reflectivities. When the background concentration of small nuclei is low, as in maritime clouds, the effect of the giant CCN is smaller and the development of precipitation is dominated by the droplets formed on large nuclei. (C) 2000 Elsevier Science B.V. All rights reserved.