The Advanced Microwave Precipitation Radiometer (AMPR) instrument played a key role in the Midlatitude Continental Convective Clouds Experiment (MC3E). The AMPR remotely senses passive microwave signatures of geophysical parameters from an airborne platform. The instrument is a low noise system which can provide multi-frequency microwave imagery with high spatial and temporal resolution. AMPR data are collected at a combination of four microwave frequencies (10.7, 19.35, 37.1, and 85.5 GHz) with two orientations each (Vpol-to-Hpol and Hpol-to-Vpol) which are complimentary to current aircraft and satellite instrumentation. These frequencies are best suited to the study of rain systems, but are also useful to studies of other atmospheric, oceanic, and land surface processes.