Photo/IllutrationLightning from thunderclouds seen from Tokyo Skytree in August 2018 (Asahi Shimbun file photo)

Japanese scientists have found a possible way to predict lightning strikes.

Teruaki Enoto, a special associate professor of space physics at Kyoto University, and his colleagues said they observed radial rays generated from thunderclouds immediately before lightning bolts light up the sky.

The phenomenon is caused by electrons speedily traveling in clouds to produce gamma rays, according to the researchers.

Enoto and the others set up gamma-ray observation instruments at two locations in Kanazawa, a city along the Sea of Japan.

In January 2018, one of the measuring devices detected a gamma-ray increase that lasted for one minute. About 20 seconds after the gamma-ray level returned to normal, lightning was reported.

Thunderbolt was also observed 30 seconds after the other device showed that the gamma-ray level started to rise, according to the scientists.

Radial rays are easier to record on land on the Sea of Japan side because thunderclouds are formed at lower altitudes there than on the Pacific Ocean side, the researchers said.

The team solicited 1.6 million yen ($14,900) through crowdfunding to install some of the observation equipment, and said it will continue to observe more thunderbolts with the assistance of citizens.

The team’s findings were published in the international physics journal Communications Physics ( on June 26.