Abstract
Simultaneous measurements of the concentration of ice particles and ice nuclei in natural clouds have shown that the concentration of ice particles can be several orders of magnitude greater than the concentration of ice nuclei effective at the cloud top temperature. However, the ratio of ice particles to ice nuclei appears to decrease sharply with decreasing cloud top temperature, and approaches a value of unity for cloud top temperatures in the neighborhood of −25C. These results suggest that the freezing of supercooled droplets is responsible for the multiplication of the number of ice particles in clouds.
