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 Iguassu

Congreso; 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 is considered 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.