Lidar.

Lidar uses laser energy in radar fashion to observe atmospheric backscattering as a function of range. The concomitant attenuation of energy along the intervening path complicates the evaluation of the observations, but even on a qualitative basis the delineation of clouds or of structure in the apparently clear air is of considerable value in operational meteorology and atmospheric research. Under certain conditions the atmosphere's optical parameters may be evaluated and related to meteorologically significant characteristics. Advanced techniques based on resonant absorption and Raman shift back- scattering are briefly noted. The current attainment and future prospects of lidar are reviewed.