| Section S | S index | 221-229 of 1376 terms |
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sedimentology—The science of the production, composition, transport, and deposition of sediment.
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seeder–feeder—Orographic precipitation-enhancement mechanism, in which precipitation from an upper-level precipitating cloud (seeder) falls through a lower-level orographic stratus cloud (feeder) capping a hill or small mountain. Precipitation droplets or ice particles fall from the higher seeder cloud and collect cloud water as they pass through the lower feeder cloud by collision and coalescence or accretion, thus producing greater precipitation on the hill under the cap cloud than on the nearby flat land. The effectiveness of the process depends on sufficiently strong low-level moist flow to maintain the cloud water content in the orographic feeder cloud and the continuing availability of precipitation particles from the seeder cloud.
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seeding devices—A generator used for producing cloud seeding particles and injecting them into clouds. The type is selected for the particular seeding material, application, and delivery system. Different types of seeding devices have been used, including combustion burners, pyrotechnic flares, atomizers, dry powder dispersal systems, dry-ice crushers, and dispensers of liquids that cool substantially on evaporation (such as propane or liquid CO2).
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seeding rate—In a cloud seeding operation, seeding rate refers to the amount of seeding material released per unit time, per unit distance traveled, or per amount of air. The amount of seeding material can be characterized by mass, volume, or number of particles.
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seeing—(Or astronomical seeing.) A term long used by astronomers for the degradation of images by the atmosphere.
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seepage spring—Spring that discharges from a saturated zone over a relatively large area.
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seepage velocity—(Also known as average actual flow velocity, average linear velocity.) The discharge (volume per unit time) per unit area of void space in a porous medium.
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