Effects of organic aerosol constituents on extinction and absorption coefficients and liquid water contents of fogs and clouds

We have speculated on the influence of organic material on extinction and absorption coefficients and liquid water content of fogs and of clouds immediately after their condensational stage. It results therefore, that the reduction of the speed of growth from fog to cloud droplets due to the presence of organic films largely reduces the properties mentioned. Compared to that their increase coming from the surface tension reduction due to organic material being dissolved or building up films is expected to be less effective.

APPROXIMATION FOR THE ABSORPTION COEFFICIENT OF ATMOSPHERIC AEROSOL PARTICLES IN TERMS OF MEASURABLE BULK PROPERTIES

The Properties of Atmospheric Aerosol Particles as Functions of the Relative Humidity at Thermodynamic Equilibrium with the Surrounding Moist Air

Publisher Summary The chapter addresses the problems in aerosol measuring techniques and selection of sampling and measuring methods. Theoretic evaluation of mass, size, mean density, and mean refractive index as functions of the relative humidity is discussed. The chapter also discusses techniques for measuring the mass as a function of the relative humidity; determination of the mean density; and measuring the mean complex index of refraction. Results of the measurements, discussion of the results, coefficients of mass increase, mean densities and real parts of the mean complex index of refractions, and applicability of the results are also described. Finally, the chapter then reviews the…

The Single-Scattering Albedo of Atmospheric Aerosol Particles as a Function of Relative Humidity

Mean bulk densities of samples of dry atmospheric aerosol particles: A summary of measured data

Mean bulk densities of various samples of dry atmospheric aerosol particles sampled at different sites and during different seasons and weather situations range between 1.8 and more than 3 gm cm3.

Humidity effects on gravitational settling and Brownian diffusion of atmospheric aerosol particles

The dependency on relative humidity of the settling velocity of aerosol particles in stagnant air and of the diffusion coefficient due to Brownian motion of aerosol particles was computed for six aerosol types and different particles sizes in dry state. The computations are based (1) on mean bulk densities of dry aerosol particles obtained from measurements or from the knowledge of the chemical composition of the particles, (2) on micro-balance measurements of the water uptake per unit mass of dry aerosol substance versus water activity at thermodynamic equilibrium, and (3) on measurements of the equilibrium water activity of aqueous sea salt solutions. The results show a significant depend…

The real part of the mean complex refractive index and the mean density of samples of atmospheric aerosol particles

The computation and the physical explanation of the spectral extinction of light in the atmosphere are mainly influenced by some specific prerequisites such as the number and the size of the atmospheric aerosol particles as well as their complex refractive index. Both size and complex refractive index are functions of the relative humidity. During the last years quite a number of investigations into the size distribution of the atmospheric aerosol particles have been carried out. Their refractive index, however is hardly known. An attempt has been made to overcome this deficiency with a new quantitative method for the simultaneous measurement of the real part of the mean complex refractive …

Approximation for the absorption coefficient of airborne atmospheric aerosol particles in terms of measurable bulk properties

The absorption coefficient of airborne atmospheric aerosol particles can be approximated by where λ is the wavelength of radiation, n — ik is the mean complex refractive index, ρ the mean bulk density, and M / V k the mass of the particles per unit volume of air. This approximation gives good results at relative humidities between 0 and 0.95 for the wavelengths of radiation between 0.55 μm and 2.0 μm and between 9.25 μm and 12.0 μm. Basing on this approximation it is possible to determine the single scattering albedo of airborne atmospheric aerosol particles with known measuring techniques. DOI: 10.1111/j.2153-3490.1977.tb00711.x