This program is organized to demonstrate the feasibility of an acoustic approach to autonomous detection, identification and measurement of hail. The sensor, which is designed to discriminate hail from rain and other forms of precipitation, is configured in a small, all solid state unit with no moving parts. Low cost, low power consumption and high reliability are all important characteristics of the approach which point toward widescale implementation at remote locations. The design, which is labeled "Characterization of Hail by Acoustic Profile" (CHAP), is based on a single-chip microcomputer for ease of interfacing with external systems.The important objectives are to determine system requirements and to develop CHAP hardware to support conclusive feasibility demonstrations. Phase I work is organized to Support advanced development of field hardware in Phase II. The potential commercial application as described by the awardee:Low unit cost in hail characterization is expected to open the door to broadscale use by federal agencies such as DOC, DOT and FAA and meteorological entities. Related technology is expected to find application in ballistics testing and in spacecraft for sensing the impact of particulates.