Droplet Charging by High Voltage Discharges and its Influence on Precipitation Enhancement

A. A. PÉREZ HORTAL; S. E. GARCÍA; R. A. COMES; G. M. CARANTI

Foz do Iguassú, Brazil

Congreso; 2010 Meeting of the Americas; 2010

American Geophysical Union

The charge on cloud droplets should increase the capture cross section to initiate and enhance coalescence. In order to test the importance of this phenomenon a twin cloud chamber was built inside a large cold room. A generator split the same amount of cloud in each chamber. One isconsidered the control and is left unperturbed, the other is the experimental one in which electrical discharges were triggered. After a free fall of 1.5m the droplet spectrum is sampled by microscope slides covered in Formvar. Comparison of these spectra show the experimental chamber has succeeded in shifting the spectrum towards larger sizes with respect to the control one. The experimental arrangement is also capable of measure charge on individual droplets by using small induction rings. Charges were measured in alternate runs with the spectral  measurements. A proportion of the droplets were charged above the average indicating that charge was deposited in them when they were inside the influence region of the corona discharge. Burst of sparks of a few centimeters long were also produced by the high voltage generator.Discussions about the relevance for cloud seeding and fog elimination are carried out.