The objective of this research is the determination of the rate of collisional growth of ice hydrometeors. This will be accomplished using both laboratory experiments and various theoretical calculations. The former will exploit an existing acoustic device (at MIT) designed to suspend selected crystals using standing sound waves. This device will be used to determine the collision efficiency between ice particles and water-ice particles. Also, electric charge separation will be measured when charged drops and ice crystals collide. Finally, the calculation of three dimensional unsteady fields of motion in the vicinity of various hydrometers will be used to interpret the experimental results. //