BINARY COLLISIONS OF SUPERCOOLED WATER DROPLETS

Binary collisions of supercooled water droplets occur in clouds and are one of the driving mechanisms of precipitation like rain or hail. All occurring binary droplet collisions also influence the clouds on a macroscopic level due to the latent heat release during phase change. To understand and observe these micro-processes, the researchers devised an experimental setup using optical levitation that is able to recreate ambient conditions in clouds. Optical levitation allows the observation of the droplet without external influences like walls or vibrations. Initial results of binary droplet collisions of supercooled water droplets are presented here. Experiments were conducted at two different temperatures, -37 degrees C and -23 degrees C, at a relative humidity of 24% and show the influence of the temperature variation and the droplet sizes, which were between 38 and 42 mu m for the falling drop and between 20 and 28 mu m for the levitated drop. The relative velocity between the two droplets was v = 2.88 m/s.