Layer structure of the troposphere

A discussion is presented of the manner in which layer-type echoes may arise and be observed using a 10cm radar at vertical incidence; such echoes are due to variations in the gaseous refractive index and not to water droplets in clouds or precipitation. Specular reflection and scattering processes are compared and the conditions indicated when an echo may be due to one or the other process, although the applicability of the turbulence theories used to relatively thin layers needs to be established. The results of the analysis are discussed in relation to data obtained from simultaneous soundings of the troposphere by radar and airborne microwave refractometers. Some comments are made regarding further experimental and theoretical investigations of the fine structure of elevated layers.