Analysis of Polarity Asymmetry Characteristics in Cloud to Ground Lightning

Observations of the differing characteristics of negative and positive cloud to ground lightning in the area of Cheyenne Mountain, Colorado between 26 July, 2018 and 24 September, 2018 are reported. A Phantom 2010 high speed camera running at 34804 to 67605 fps was utilized for these observations. 16 negative cloud to ground strikes and 5 positive cloud to ground strikes were detected. Inspired by Williams's 2006 paper on the impact of polarity on lightning physics, analysis of the characteristics corresponding to lightning polarity focused on the current flow in the channel, the amount of strikes observed on a single channel, the behavior of the stepped leader, and the presence of cloud to cloud lightning surrounding the return stroke. Our observations showed that positive lightning displayed evidence of a continuous current after the return stroke, while negative lightning showed a lack of continuous current, and instead had multiple strikes in the same channel. Negative cloud to ground strikes were typically preceded by a stepped leader, whereas positive lightning often did not have any visible stepped leader. In many observed cases, when a positive cloud to ground strike occurred, there was also cloud to cloud lightning visible in surrounding clouds; this cloud to cloud lightning was not observed for negative cloud to ground strikes. Future work will include comparing this data to lightning observed on Cheyenne Mountain in the year 2019 in order to understand the repeatability of these observations and further characterize cloud to ground lightning.