Laser Light Backscattering from Laboratory Aerosols

Measurements of laser light backscattering vs. humidity for salt aerosols

“…Electron microscope pictures of the samples on the foil were taken at 10,000X magnification, and sizing was done by comparing the area qf the particles to the areas of circles. Size information is given in Table I and Figure solutions is on the order of incident light wavelength (Charlson et al, 1967;Cooper and Byers, 1970;Noll et al, 1968). The smallest particles were least accurately sized.…”

“…Particles which contribute most significantly to natural light scattering in the atmosphere are those of about V2 µ in diam (Pueschel and Noll, 1967), and for aerosols of approximately this size the scattering is nearly proportional to the particle volume (Charlson et al, 1967;Cooper and Byers, 1970). The volume mean diameters of the aerosols used in this work were approximately 0.2-0.4 µ and the volume median diameters were 0.6-1.5 µ. Measurements made by Whitby et al (1972) in Pasadena, Calif., gave a bimodal size distribution for the atmospheric aerosol, which in the light-scattering size region approximated a log-normal distribution of 0.3-µ median diam and 2.25 geometric std dev, quite similar to the aerosols used here.…”