Radar measurements of mammatus characteristics have been extremely scarce and often conducted by scanning airborne or ground based radar that lack the resolution needed to resolved the small scale features of mammatus clouds. Three processes related to their formation have been identified: subsidence of a cloud interface layer, fallout of precipitation, and evaporation of precipitation. In this paper, we report on unprecedented high-resolution W-band Doppler radar observations of mammatus clouds observed during the CRYSTAL-FACE experiment conducted in South Florida on July 21, 2002. The observations were taken as thick cirrus clouds produced by deep convection over the ocean advected over a surface site located at Tamiami Airport. The fine structure of individual mammatus clouds is presented and significant velocity perturbations are recorded. Areas of mixing involving cloudy and subcloud air are identified and the role of gravity waves on mammatus cloud formation is investigated. Examples of recorded Doppler spectra are shown that illuminate the microphysical processes and modification of the distribution of ice crystals as they reach the cloud base.