Relationship between particle size and imaginary refractive index in atmospheric dust.

The scientific community involved in propagation of visible and ir radiation in the earth's atmosphere and those workers concerned with the solar heating of the atmosphere are necessarily interested in the imaginary refractive index of atmospheric dust. This information is needed to describe radiation absorption effects quantitatively using Mie theory. In such calculations, almost without exception, a single value of the imaginary index is used at any one wavelength regardless of particle size of the dust. However, the work of Blanco and Mclntyre has shown that the composition of atmospheric dust varies strongly with particle size, a result that one should quite reasonably expect since many different processes contribute to the dust in air. It has been pointed out earlier that the imaginary indices for different materials commonly found