Image blur due to forward scattering from atmospheric aerosols: retrospective

Atmospheric degradation of image quality has been observed and studied for centuries. In more modern times, atmospheric blur has usually been entirely attributed to atmospheric turbulence alone. The role of airborne particulates or aerosols was usually assumed to be limited to attenuation and contrast reduction. However, in the late 1970s, it began to become apparent to observers in different locations that aerosols not only attenuate images but also give rise to noticeable blur with hardly any connection to turbulence. The purpose of this retrospective is to try to summarize these findings, beginning with development of my own interest in the field.