Growth mechanisms and size spectra of photochemical aerosols

Journal Article · Mon Jan 01 04:00:00 EST 1973 · Environ. Sci. Technol.; (United States)

DOI:https://doi.org/10.1021/es60075a003· OSTI ID:5480230

Husar, R B; Whitby, K T

A series of photochemical aerosol aging experiments were performed in which the complete time-dependent size spectra (diameter range 0.004 < dp < 0.35 micrometers) were measured using a Whitby aerosol analyzer. Based on these data, the role of various physical mechanisms, i.e., nucleation, coagulation, and condensation in the photochemical aerosol formation is identified. In an initially particle-free system, the aerosol passes through the following stages of evolution: nucleation-condensation (simultaneously), nucleation-condensation-coagulation, and condensation and coagulation. If suitable foreign nuclei are present, in sufficient quantity, the gas-to-particle conversion occurs preferentially on the existing nuclei, i.e., the nucleation is heterogeneous. Available laboratory and atmospheric data indicate that whether homogeneous or heterogeneous nucleation occurs in the atmosphere depends on the relative amount of surface area provided by foreign nuclei. There is evidence that in Los Angeles smog, the nucleation occurs heterogeneously, while in sparsely populated areas the nucleation is homogeneous.

• OSTI ID: 5480230
• Journal Information: Environ. Sci. Technol.; (United States), Journal Name: Environ. Sci. Technol.; (United States) Vol. 7:3; ISSN ESTHA
• Country of Publication: United States
• Language: English

Related Subjects

500100* -- Environment
Atmospheric-- Basic Studies-- (-1989)
54 ENVIRONMENTAL SCIENCES
ACID RAIN
AEROSOLS
ATMOSPHERIC PRECIPITATIONS
CHEMISTRY
COLLOIDS
DISPERSIONS
MATHEMATICAL MODELS
PARTICLES
PARTICULATES
PHOTOCHEMISTRY
RAIN
SOLS