As you can imagine, a team of researchers—that includes Victor Pasko, a professor of electrical engineering at Penn State University—has made impressive headway. They are unraveling the different processes that cause lightning to occur. Last week, they published one of those studies—their own groundbreaking study—in the Journal of Geophysical Research on July 28, 2023. This study proposed a new model, named Photoelectric Feedback Discharge. This unique model shows the amazing chain reaction that powers lightning. It’s teaching them about the atmospheric conditions required for lightning to even occur.
Now, Pasko’s team utilized advanced mathematical modeling to explore and determine the interaction of cosmic rays with Earth’s atmosphere. Among their findings was the production of relativistic energy electrons from these interactions. Making electrons in this manner can eventually help to produce the incredible energy discharge that creates lightning strikes. These results agree with the patterns seen in the field. They not only demystify the physics at play with this beautiful natural phenomenon.
The Role of Cosmic Rays and Electrons
The discovery shows that cosmic rays coming from outer space into Earth’s atmosphere actually generate relativistic energy electrons. Once inside of an electric field of a thunderstorm, these very high-energy particles experience a dramatic increase in number. These accelerated electrons then crash into atmospheric molecules such as nitrogen and oxygen. This collision emits X-rays and initiates a cascade of secondary electrons and high-energy photons.
Victor Pasko emphasized the significance of their findings, stating, “Our findings provide the first precise, quantitative explanation for how lightning initiates in nature.” He further elaborated on the connection between different phenomena by saying, “It connects the dots between X-rays, electric fields and the physics of electron avalanches.”
The research shows that this electrochemical process is responsible for creating the necessary conditions for lightning bolts to arise. These powerful electric fields inside thunderclouds not only accelerate the electrons but kickstart a runaway chain reaction. This chain reaction can occur in low volumes and its potency can differ substantially. It usually creates observable X-ray emission, yet displays almost no optical and radio emissions at all.
Simulating Thunderstorm Conditions
Zaid is a doctoral student in the Department of Electrical Engineering. In the research, he was the one who tried to match the field observations to the simulated conditions created in thunderclouds by the new model. Read more about the team’s extensive data collection, which involved grounding-based sensors, satellites and high-altitude surveillance aircraft.
Pervez explained the importance of their approach: “We explained how photoelectric events occur, what conditions need to be in thunderclouds to initiate the cascade of electrons, and what is causing the wide variety of radio signals that we observe in clouds all prior to a lightning strike.” This groundbreaking, long-term collaborative analysis aims to fill the voids of prior studies and provides an exciting new layer of understanding about how lightning is initiated.
To confirm his results, Pervez cross-validated his findings against the output of previous modeling studies. He cited his own research on compact intercloud discharges, lightning events that typically occur in small patches inside thunderclouds. His efforts emphasize the teamwork aspect of this research, utilizing various scientific fields.
Implications for Future Research
The significance of this study goes beyond just academic interest. Gaining a better grasp on the mechanisms that cause lightning would have immediate benefits to disciplines that rely on lightning data, like meteorology and aerospace safety. Pasko’s model provides an overall explanation for the X-rays and radio emissions seen in thunderclouds. This special contribution advances our scientific understanding of atmospheric phenomena.
Pasko articulated the broader significance of their work: “In our modeling, the high-energy X-rays produced by relativistic electron avalanches generate new seed electrons driven by the photoelectric effect in air, rapidly amplifying these avalanches.” This new understanding has the potential to inform better predictive models for lightning strike risk and better protective industrywide safety protocols.
This project drew on the expertise of diverse institutions, led by co—authors representing them. Among them were Sebastien Celestin from the University of Orléans, France, Anne Bourdon from École Polytechnique, France, Reza Janalizadeh from NASA Goddard Space Flight Center, Jaroslav Jansky from Brno University of Technology, Czech Republic, and Pierre Gourbin from Technical University of Denmark. Their combined knowledge and skills highlight just how complex the study of our atmosphere can be.