GEOG 1112 Lecture Notes - Lecture 12: Supercooling, Ice Nucleus, Cloud Condensation Nuclei

• School: University of Georgia
• Department: Geography
• Course: GEOG 1112
• Professor: James Shepherd

Document Summary

Cloud & rain droplets: highly curved drops require supersaturation to offset evaporation. Solute effect (material dissolved in water) reduces the amount of supersaturation: curvature effect is approximately balanced by solute effect to enable. Nucleation types: hygroscopic (water attracting) aerosols enable heterogeneous nucleation closer to 100%, homogeneous nucleation (no aerosols) require large relative humidities--not common. Initially cloud droplets can grow by condensation of water vapor: there is limited water vapor and a lot of condensation nuclei competing for the water, thus, none will grow very big, other processes are needed for further growth Growth in warm clouds: most clouds in the tropics and some in the middle latitudes are warm clouds - those with temperatures above freezing. In these clouds, the collision-coalescence process causes precipitation. Collision and coalescence: larger drops collect smaller drops & grow, must collide and coalesce to grow.