. Compendium of meteorology. Meteorology. 1128 BIOLOGICAL AND CHEMICAL METEOROLOGY subsequently deposited.^ As a result of thermal convec- tion, this process is continuous in the newly advected air, and fog particles, proportional in number to the mass of air flowing close to the metallic surface, adhere to it and finally drip off into a graduated tapered vessel. The condensation apparatus (Fig. 2) consists of an egg- shaped dew-cup which is plated with Cr or Ni, is well- polished, and has a capacity of two liters of ice Fig. 2.—Apijaratus for the analysis of traces which form condensa
. Compendium of meteorology. Meteorology. 1128 BIOLOGICAL AND CHEMICAL METEOROLOGY subsequently deposited.^ As a result of thermal convec- tion, this process is continuous in the newly advected air, and fog particles, proportional in number to the mass of air flowing close to the metallic surface, adhere to it and finally drip off into a graduated tapered vessel. The condensation apparatus (Fig. 2) consists of an egg- shaped dew-cup which is plated with Cr or Ni, is well- polished, and has a capacity of two liters of ice Fig. 2.—Apijaratus for the analysis of traces which form condensation nuclei. Center, Cauer condensation dew-cup; at right, Assman psyohrometer; below, thermohygrograph. During the time required for the dew deposit, 20 min in most cases, the mean absolute water content of the air must be determined in the immediate vicinity with the aid of an Assmann psychrometer or a thermohygro- graph. Depending on the number of analyses and the substances to be investigated, amounts of condensate ranging from 1 to 20 cc are collected. During ventilation the sphere must be shielded from direct sunlight and dust. Hence it cannot be used during storms; likewise, it cannot be used when the absolute humidity of the air is small. During cold weather a coating of hoarfrost is produced by charging the sphere with a refrigerant. Insofar as possible, the chemical substances are ana- 1. The direct condensation of steam on cooled, polished, metal surfaces without the existence of condensation nuclei amounts to almost one per cent of the total possible precipita- tion, according to Mayer [39] (this percentage also includes the direct condensation on the surface of the water). This occur- rence is so low that the validity of the following chemical analysis is not affected. lyzed by the methods usual in water analysis [47]. For other substances special trace-detection methods are used, for example, spot analyses [15, 24]. The number of analyzable substances can be inc
Size: 1372px × 1821px
Photo credit: © The Book Worm / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookcentury1900, bookcollectionbiodivers, booksubjectmeteorology
