New Cosmic Mechanism Revealed For How Lightning Forms Through Electric Fields And Electrons

Researchers at Pennsylvania State University, led by Victor Pasko, have made a significant discovery about how lightning begins. Their study provides the first detailed explanation of this natural phenomenon. They found that strong electric fields in thunderclouds accelerate electrons, causing them to collide with molecules like nitrogen and oxygen. This collision produces X-rays and triggers a cascade of electrons and high-energy photons, leading to lightning.

The research team used mathematical models to replicate field observations of photoelectric phenomena in Earth's atmosphere. These phenomena occur when cosmic rays from space enter the atmosphere, causing electrons to multiply in thunderstorm electric fields. This process emits brief bursts of high-energy photons known as terrestrial gamma-ray flashes.

Pasko explained that their findings connect the dots between X-rays, electric fields, and electron avalanches. "Our findings provide the first precise, quantitative explanation for how lightning initiates in nature," he stated. The study was published in the Journal of Geophysical Research and offers insights into the physics behind these natural events.

The model developed by Pasko's team simulates conditions under which lightning is likely to originate. It explains why terrestrial gamma-ray flashes often occur without visible light or radio emissions, which are typical during storms. The equations used in their model are available for other researchers to explore further.

Zaid Pervez, a doctoral student involved in the study, used the model to match field observations collected by various research groups using ground-based sensors and satellites. He explained how photoelectric events occur and what conditions are necessary within thunderclouds for electron cascades to begin.

Pervez compared their results with previous studies on compact intercloud discharges—lightning that occurs in small regions within thunderclouds—to confirm their explanation of lightning initiation. This comparison helped validate their findings against existing data and models.

Gamma-Ray Flashes Without Light

Pasko noted that high-energy X-rays produced by relativistic electron avalanches generate new seed electrons through the photoelectric effect in air. This rapidly amplifies these avalanches, sometimes resulting in detectable X-rays with minimal optical and radio emissions.

"In addition to being produced in very compact volumes, this runaway chain reaction can occur with highly variable strength," Pasko added. This explains why gamma-ray flashes can emerge from regions that appear dim or silent optically and radio-wise.

This research not only advances our understanding of lightning initiation but also sheds light on why certain gamma-ray flashes occur without accompanying light or sound during storms. The team's work provides a comprehensive view of these complex atmospheric processes.

With inputs from WAM