An Instrument for the Simultaneous Measurement of the Image and Electric Charge of Hydrometeors

Abstract

While past measurements of electric charges on cloud particles have led to some advances toward ascertaining the mechanisms of charge generation, it became evident that an important part of the problem is still unsolved, namely a one-to-one identification of the type of hydrometeor with its electric charge. In order to help solve this problem, an instrument has been developed which allows for the simultaneous measurement of a hydrometeor's shadow-graph and electric charge. The device consists of an induction ring mounted directly behind the sampling aperture of a modified PMS 2D-C probe. The charge information generated as the particle passes through the induction ring is digitally sampled 32 times using a clock synchronized to the particle's position in the ring and these values are stored within the 2D data buffer directly after the image data. This probe may be flown with any data acquisition system capable of recording 2D data. Details of probe operation and calibration results are given along with some preliminary flight data from the Wyoming King Air.