GGR214H5 Lecture Notes - Lecture 6: Ice Nucleus, Supercooling, Ice Crystals
Document Summary
Favourable aerosols are wettable, large, and hygroscopic, the more soluble, the more effective, sources of ccn. Over oceans: sea salt, dimethyl sulphide produced by phytoplankton. Nucleation below freezing: the temperature at which droplets will freeze depends on their size. Ice nuclei promote the formation of ice crystals: allow heterogeneous nucleation. Favourable ice nuclei are large and insoluble: clay minerals, combustion products, organic material. Cloud formation: clouds form due to rising air, five basic mechanisms by which air rises to form clouds. The classification of clouds: classification is based on form and height, howard"s identification system uses latin roots, cumulus ( heap , stratus ( layer , cirrus ( curl of hair , nimbus ( rain ) Low clouds: less than 2 km above sea level, may be water or a mixture of water and ice. Middle clouds: from 2 km up to 3 6 km (lower at high latitudes)
