Source of X-rays in thunder

Researchers at the University of Florida and the Florida Institute of Technology have narrowed down the search for the source of X-rays generated by lightning, which could one day help predict the location of lightning.

Joseph Dwyer, professor of physics and space science at FIT, said: 'From a practical point of view, in order to predict the timing and location of lightning strikes, we first need to understand how lightning moves. from one place to another. Currently, we have not handled this well. X-rays give us a close look at what happens inside while lightning moves. '

An article detailing the recent UF and FIT team's findings has been published online in Geophysical Research Letters, published by the American Geophysical Association.

The researchers used an electric field plate and X-ray detector at the UF / FIT lightning research facility to search for X-ray sources generated by lightning. Their main conclusion is: When lightning moves from the cloud to the ground in a 30 to 160 minute path, called the 'step' in the 'lead step' process, X-rays appear just below each step. , about 1/100 million seconds after one step ends.

Researchers have narrowed the search for the source of X-rays generated by lightning, which could one day help predict the location of lightning.(Photo: iStockphoto / Shane Shaw)

Martin Uman, professor of electrical and computer engineering, said: 'Nobody understands how lightning produces X-rays. Despite achieving a five-fold hotter temperature, the temperature of the lightning is still too low. to form X-rays'.

Uman continued: 'But that obviously happened. We have set limits for the conditions it can occur and where it happens. '

Since 1925, theorists have predicted that thunderstorms can produce X-rays. However, scientists have sought evidence for decades that have not achieved any significant success. Then in 2001 and 2002, researchers at the New Mexico Institute of Mining and Technology, University of Florida and the Florida Institute of Technology firmly confirmed that lightning actually produced a large amount of X-rays. Since then, scientists all over the world have constantly sought to understand and explain this phenomenon.

Researchers at the New Mexico Institute of Technology have detected high energy radiation from natural lightning. The UF / FIT International Experimental Lightning Research Center, located at a military base in Clay County, created lightning by firing a cannon at a passing storm cloud. In 2002, Uman's team said that "lightning excitation" also produced X-rays.

In the latest study, electrical engineering PhD student Joey Howard, the lead author of the paper, and other UF / FIT researchers used a variety of electric field detectors and sodium X-ray detectors. loaf to try to probe X-rays at closer range.

In the 2002 paper, UF / FIT scientists confirmed the X-ray of the main lightning step. In the latest article, they narrowed the time to form X-rays to the beginning of each step in the main lightning step, based on data collected from a natural lightning bolt and a stimulating lightning bolt.

Uman said: 'We can determine the time of the electric field to the station series, which coincides with the time of X-ray occurrence. Then we return and calculate the source position of the electric and X-rays'.

Dwyer said the study is a step towards using X-rays to capture the movement of lightning.

He said: 'A bolt of lightning starts inside a thunderstorm somehow moving many miles to the face, can hurt people and property. This is the first time we can really observe the motion of lightning on the ground with X-rays. So it's like X-rays help a doctor see better during surgery, it also allows us to visit detect every process of lightning - something very difficult to do '.

Uman said the study will continue with more expensive, fast and sensitive X-ray detectors. Another interesting area in the future is whether lightning strikes the aircraft can produce X-rays that affect passengers.