What is the feature of rising lightning?

Unlike traditional lightning that originates in clouds and strikes downward, positive upward flashes begin from negatively charged channels at high altitude. These channels gradually rise before connecting to the storm cloud and transferring positive charge to the ground.

These flashes differ from others in that their X-rays can be detected and measured, providing valuable information that could help alleviate the devastating effects of lightning around the world.

Why is this important?

Detecting X-rays during upward lightning is particularly important because of its potential to cause more damage than traditional downward lightning strikes, Oregel-Chaumont said. This is explained by the prolonged contact between lightning and structures during upward lightning strikes, which provides a more significant transfer of electrical charge.

Although X-rays have previously been detected in various forms of lightning, including downward cloud-to-ground strikes and upward negative lightning, their observation at the blast channel stage of upward positive lightning is a new development.

Researchers emphasize the importance of this discovery for solving mysteries about the initiation and propagation of lightning.

More about the study

Research conducted on the Zentis Tower in Switzerland took advantage of its strategic location atop the Zentis mountain in the Appenzell Alps. Serving as both a telecommunications tower and a weather station, the tower is frequently struck by lightning, creating ideal conditions for scientific observations.

Zentis Tower in the Appenzell Alps / Photo: EPFL

High-speed cameras installed by the researchers captured rare upward flares, allowing detailed analysis at unprecedented speed.

The key findings of the study revealed distinct properties of upward flares that produce positive X-rays, including their short duration and correlation with rapid changes in the electric field. This information is important for engineering applications, especially for the design of structures sensitive to lightning strikes.

Oregel-Chaumont emphasizes the importance of combining scientific understanding with practical application, especially in the context of modern structures that are increasingly built from non-conductive materials, such as wind turbines and aircraft. By understanding the dynamics of surge lightning and its associated risks, researchers are trying to develop strategies to protect these structures from potential damage.