Note on aerosol scattering in India

Abstract

A critical examination of the wavelength exponent ~ embodied in the well-known ANGSTR6M'S proposition for coefficient of aerosol scattering expressed by mh~8)~-a has been made. It is observed that, in North and Central India, for most part of the year the exponent a is zero and sometimes even negative. This shows that the aerosol scattering is independent of wavelength and neutral. The existance of the negative values of the exponent in India has been discussed here in the light of aerosol size distribution. It is proposed that, for routine purposes, the assumption ~ = 0 would be reasonably good in North and Central India during sommer season. During winter, ~ has a mean value of about 1.0. However, it is better to determine the exact value of ~ in each case while evaluating the turbidity coefficient.

Time variations of turbidity parameters in the Madrid atmosphere

“…The minimum value observed was c~ = --1.4 (July 11, 1978 at 1200 GMT). The phenomenon of anomalous extinction has been observed often [11,12,13,14]. Possible causes for this anomaly are [14]: the presence of a stratospheric semi-monodisperse aerosol, and/or absorption effects in the visible part of the spectrum with clear moist air and the presence of ozone aloft.…”