Abstract: A laser echoe ranging device (lidar) is used both to measure cloud height and to measure slant range visibility. For the latter purpose at various elevation angles, the distance for which the echoe gets down to the noise level is measured by a counter and the echo voltage for a distance selected by a time switch is also stored, for example for various distances in 100 meter steps. These values can be used to compute the slant visual range and, with reference to the data for the different angles of elevation, also the layer structure of an inhomogeneous scattering characteristic of the atmosphere.