Charging Effect on the 80-200 nm Size Atmospheric Aerosols during a Lightning Event

ABSTRACT

Atmospheric aerosol charging is caused mainly by cosmic rays and/or natural radioactive material decay. Because the ionization process generates well-balanced ion pairs, positive and negative ions in the air are at almost the same concentrations. The atmospheric aerosol electrical charge is therefore usually neutral. We measured the particle charge polarity distribution in the atmosphere during a lightning event at ground level. We found that the 80–200 nm particle charge balance during a lightning event was skewed either to the positive or the negative. Furthermore, the particle charge polarity changed very rapidly (within a few minutes) from negative to positive or vice versa. There was also a two-fold higher charged particle fraction during a lightning period than a normal day. This increased charged particle fraction may decrease the total particle concentration in the atmosphere by deposition on raindrop surfaces.