The History of Radar Studies of the Clear Atmosphere

The investigation of radar echoes from the clear atmosphere has interested scientists since the mid-1930s when long-wavelength radars, used for ionospheric measurements, detected reflecting layers in the troposphere. The challenge of explaining the radar echoes from the clear atmosphere has often proved to be a major difficulty because of the possibility of at least two explanations for each of the various types of echoes observed. The challenge was always intriguing, and as the explanations of the echoes became accepted, a rapid rush of scientific results arose as new radar systems were applied to studies of atmospheric structure and dynamics.