The solution of electromagnetic scattering by a homogeneous prolate (or oblate) spheroidal particle with an arbitrary size and refractive index is obtained for any angle of incidence by solving Maxwell's equations under given boundary conditions. The method used is that of separating the vector wave equations in the spheroidal coordinates and expanding them in terms of the spheroidal wavefunctions. The unknown coefficients for the expansion are determined by a system of equations derived from the boundary conditions regarding the continuity of tangential components of the electric and magnetic vectors across the surface of the spheroid. The solutions both in the prolate and oblate spheroidal coordinate systems result in a same form, and the equations for the oblate spheroidal system can be obtained from those for the prolate one by replacing the prolate spheroidal wavefunctions with the oblate ones and vice versa. For an oblique incidence, the polarized incident wave is resolved into two components, the TM mode for which the magnetic vector vibrates perpendicularly to the incident plane and the TE mode for which the electric vector vibrates perpendicularly to this plane. For the incidence along the rotation axis the resultant equations are given in the form similar to the one for a sphere given by the Mie theory. The physical parameters involved are the following five quantities: the size parameter defined by the product of the semifocal distance of the spheroid and the propagation constant of the incident wave, the eccentricity, the refractive index of the spheroid relative to the surrounding medium, the incident angle between the direction of the incident wave and the rotation axis, and the angles that specify the direction of the scattered wave.

A method of evaluating the aerosol size distribution from the spectral attenuation measurements is shown. The process consists of solving the simultaneous integral equations, and examples are given of solutions based on the attenuation measurements made by Knestrick et al. over the Chesapeake Bay. It is found that the evaluated individual size distributions do not necessarily follow the power law, although departures from it are mostly small. If the power law is to be adopted neglecting small departures, the evaluated results are in average expressed by r(-3.57), where r is the radius of aerosols. In this study, the refractive index of aerosols is assumed to be 1.50, and some discussion is made of the effect of adopting a different refractive index value on estimation of the size distribution.

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Recently Hanel [1961] made the interesting suggestion that the estimation of cloud‐top altitude is possible by measuring from a satellite the absorption of reflected solar radiation by a CO2 band. We agree with this suggestion in principle, but at the same time we consider that the reflected ray from the cloud top must be strong and that its absorption by the medium above the cloud must be considerable. The choice of the absorption band is therefore very important for this problem. Hanel proposed the use of the 2 μ CO2 band.

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