ATOC 5600 Physics and Chemistry of Clouds & Aerosols

  Introduction

The characteristics of aerosols (number concentration, size distribution, chemical composition) have a large impact on when and where a fog layer will form. Also, due to the strong link between aerosol characteristics and fog microphysics, the overall life cycle of a fog layer is influenced by these aerosols. Indeed the fog layer liquid water content, drop size distribution and thus visibility will be modified according to the characteristics of aerosols contained in the air mass. A better understanding of fog formation and characteristics is important for weather prediction purposes (necessary for improved security of air travel and ground transportation) (Bergot and Guédalia, 1994; Stoelinga and Warner, 1999) as well as determining its impact on ecosystems. 

Fogs forming in polluted areas act as efficient mechanisms for the deposition of some chemical species on vegetation (wet deposition) (Lovett and Kinsman, 1990). Aqueous-phase chemical reactions are taking place in fog droplets (Facchini et al., 1992) and when these drops evaporate after settling on vegetation, they leave behind  concentrated chemicals that may be detrimental to vegetation growth. Also, fog water represents an important resource for people living in arid regions (Amedie, 2001). Fog water collectors have been developed so that fogs can be used as a source of irrigation and drink water. Consequently, knowing and understanding the chemical composition of fog water is important for health and agricultural productivity issues. 

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