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Wet Deposition
Before beginning the discussion on wet deposition, some general comments on deposition mechanisms. Aerosol particles have surfaces on which gases and tiny particles can be adsorbed. When breathed in, these particles are deposited into the tissues of the lungs, causing greater toxicities than "plain" particles. When gases are adsorbed, they are removed. Dry deposition is typically defined as the settling of gases and particles out of the atmosphere. Dry deposition is a component of acid deposition, more commonly referred to as acid rain. Wet deposition is the process by which chemicals are removed from the atmosphere and deposited on the Earth's surface via rain, sleet, snow, cloudwater, and fog Deposition, in general, refers to the transfer of airborne pollutants to the earth's surface where they either react with or adhere to some surface and thus, are removed from the atmosphere. Wet deposition involves the absorption of pollutants, both particles and gases, into liquid droplets or ice crystals. These pollutants are transferred, in most cases, to the surface in the form of precipitation. Wet deposition is also commonly referred to as precipitation scavenging, wet removal, rainout, and washout. However, wet deposition is not limited to precipitation. It also includes the deposition that occurs when low lying fog or haze droplets come into contact with a surface such as plant life or natural and man-made structures. Acid rain and acid fog are two examples of wet deposition that can adversely affect the surfaces onto which they are deposited. Module 7: Physical Meteorology and Visibility will discuss, in detail, the role of aerosols and other pollutants in cloud droplet and ice formation and their significance to cloud physics and the production of fog, haze, and smog.Confused? Have a question? If so, check out the Frequently Asked Questions (FAQ) page or send mail to the OS411 tutor (os411tutor@shodor.org) with your question! Report technical/content problems here |
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