Zurich, Switzerland – When we think of lightning, we typically picture it striking downward from the sky in a powerful display of electricity. But scientists have recently made a groundbreaking discovery that challenges this conventional view.
Researchers at the Swiss Federal Institute of Technology (EPFL) have detected and measured the emission of X-rays in a unique type of lightning known as upward positive flashes. These flashes, which move in an upward direction towards the sky, start at high altitudes with negatively charged leaders before connecting with a thundercloud and transferring a positive charge to the ground.
The detection of X-rays in these upward positive flashes could potentially provide valuable insights into the formation and behavior of lightning, ultimately helping to reduce the damage caused by these powerful natural phenomena.
According to astrophysicist Toma Oregel-Chaumont, who led the research team, upward flashes are relatively rare at sea level but could become more common at higher altitudes. These flashes have the potential to be more destructive than traditional downward strikes, as they remain in contact with structures for longer periods, allowing for more extensive electrical charge transfer.
The team’s study, which focused on lightning flashes erupting from the Säntis Tower in Switzerland, involved the use of high-speed cameras to capture the phenomenon at an astonishing rate of 24,000 frames per second. This unique vantage point provided researchers with valuable data on the behavior of upward positive flashes and the emission of X-rays during the leader formation phase.
The researchers observed that X-ray emission in upward positive flashes is brief, disappearing within the first millisecond of leader formation. This rapid emission of X-rays correlates with significant changes in the electric field and current, shedding light on the mechanisms underlying lightning strikes.
The implications of this research extend beyond scientific curiosity, as Oregel-Chaumont notes that understanding lightning behavior is crucial for engineering purposes. With the rise of high-altitude structures such as wind turbines and aircraft constructed from composite materials, the susceptibility to damage from upward lightning strikes increases.
By gaining a deeper understanding of the physics behind lightning formation, researchers hope to develop strategies to mitigate the destructive impact of these natural electrical discharges on human-made structures. The team’s findings have been published in the journal Scientific Reports, marking a significant step forward in our understanding of lightning phenomena.