Laser Radar Echoes from the Clear Atmosphere

USING experimental pulsed ruby laser radars, numerous observations have been made hero of echoes from the ‘clear’ atmosphere. There is no doubt that these returns are caused by backscattering from particulate matter in the aerosol. Even in the clearest conditions echoes are invariably obtained from the immediate vicinity, and these are much enhanced in hazy conditions. Strong signals are commonly noted at heights corresponding to low-level inversions, revealing haze layers which are not discernible by eye.