The Roles of Mineral Dusts and Coastal Aerosol in Cold and Warm Cloud Formation.

摘要

The indirect effect of atmospheric aerosol is one of the largest uncertainties in determining the Earth's radiative budget. This uncertainty has been attributed to our lack of understanding of processes leading to cloud formation. Consequently, this thesis investigates the abilities of two main types of aerosol to form warm and mixed-phase clouds.;To study the mixed-phase cloud formation properties of 24 atmospherically-relevant minerals, their deposition ice nucleation properties were studied using a single experimental method. From a set of minerals present in mineral dusts it was found that feldspars were the most efficient ice nuclei. In addition, the warm cloud formation properties, or hygroscopicity (e), of coastal ambient aerosol and its organic components were investigated in Ucluelet, BC. While the e of 50 nm and 100 nm particles exhibited a wide size-independent variation (0.14 - 1.08), the e of its organic fraction was estimated to be between 0.3 and 0.5.