Mystery of the century solved: Where does lightning come from?

For centuries, lightning has been a mysterious natural phenomenon, explained by myths and legends.

Although modern science has determined that lightning is a giant electric current that travels through the air, its deep origin remains a big question.

Now, an international team of scientists led by Penn State University (USA) has published the answer, revealing a complex and silent chain of reactions that takes place inside the cloud before the actual lightning appears.

Lightning is not a sudden electrical discharge, according to new research in the Journal of Geophysical Research: Atmospheres .

Instead, the process begins with cosmic rays – high-energy particles from space that collide with Earth's atmosphere.

As these rays pass through a thundercloud, they create fast-moving electrons. In the cloud's strong electric field (created by collisions between ice and water particles), these electrons are further accelerated, crashing into air molecules such as nitrogen and oxygen, producing X-rays and high-energy photons.

This process is likened to a "grain avalanche", where an initial grain triggers the formation of a series of new grains, eventually leading to the formation of lightning.

What's remarkable is that this entire reaction takes place without any light or thunder, leaving humans unaware until the lightning actually strikes.

"This is the first time we have a fully quantitative model that explains how lightning forms in nature, connecting X-rays, electrons and electric fields in clouds," said Professor Victor Pasko, who led the research team.

To test the hypothesis, the team used computer simulations combined with real-world data from satellites, ground sensors and specialized aircraft.

The results showed that the model matched field observations perfectly, especially for terrestrial gamma-ray bursts – powerful bursts of radiation that often appear during thunderstorms but are not accompanied by thunder or lightning.

This explains why there are "lightning strikes" without any flash, because the reactions occur in very small volumes, sometimes only creating weak X-rays that are invisible to the naked eye and inaudible to the human ear.

This model, which the team calls “Photoelectric Feedback Discharge,” was first published in 2023 and has now been verified.

This discovery not only sheds light on a familiar natural phenomenon but also opens up new research directions on the impact of the universe on Earth's climate, as well as the interaction between elementary particles and the natural electromagnetic environment.

This is an important step forward, promising applications in weather forecasting, disaster warning and aviation safety.

Source: https://dantri.com.vn/khoa-hoc/bi-an-the-ki-duoc-giai-dap-set-hinh-thanh-do-dau-20250807081406642.htm