A Technique for the Measurement of Cloud Structure on Centimeter Scales

Abstract

A system has been developed for measuring the distance between cloud droplets along the flight path with an airborne optical particle counter. This technique resolves separation distances as small as 0.2 mm at a typical flight speed of 100 m s?1, a measure of cloud structure at scales much smaller than previously possible. This technique also provides an important alternative measure of droplet concentration that is negligibly affected by coincidence and dead-time losses. This new measurement technique may lead to a better understanding of cloud processes by providing the means of examining clouds at scales that are important in determining rates of droplet growth and evaporation. The capability of measuring droplet concentrations that are unbiased by coincidence and dead-time losses is a major offshoot of this technique and removes much of the uncertainty that has hampered previous measurements with optical particle probes.