Featured Research

from universities, journals, and other organizations

Scientists Close In On Source Of X-rays In Lightning

Date:
July 16, 2008
Source:
University of Florida
Summary:
Engineering researchers have narrowed the search for the source of X-rays emitted by lightning, a feat that could one day help predict where lightning will strike.

Engineering researchers have narrowed the search for the source of X-rays emitted by lightning, a feat that could one day help predict where lightning will strike.
Credit: iStockphoto/Shane Shaw

University of Florida and Florida Institute of Technology engineering researchers have narrowed the search for the source of X-rays emitted by lightning, a feat that could one day help predict where lightning will strike.

“From a practical point of view, if we are going to ever be able to predict when and where lightning will strike, we need to first understand how lightning moves from one place to the other,” said Joseph Dwyer, a professor in the department of physics and space sciences at FIT. “At present, we do not have a good handle on this. X-rays are giving us a close-up view of what is happening inside the lightning as it moves.”

An article detailing the UF and FIT team’s findings recently appeared in the online edition of Geophysical Research Letters, published by the American Geophysical Union.

The researchers used an array of electric field and X-ray detectors at a UF/FIT-operated lightning research facility in North Florida to hunt the source of X-rays emitted by lightning strokes. Their main conclusion: As the lightning comes down from the cloud toward the ground in 30- to 160-foot stages known as “steps” in a “step leader” process, the X-rays shoot out just below each step, mere millionths of a second after the step completes.

“Nobody understands how lightning makes X-rays,” said Martin Uman, a professor of electrical and computer engineering. “Despite reaching temperatures five times hotter than the surface of the sun, the temperature of lightning is still thousands of times too cold to account for the X-rays observed.”

That said, Uman added, “It’s obviously happening. And we have put limits on how it’s happening and where it’s happening.”

As far back as 1925, theorists predicted that thunderstorms and lightning might make X-rays. However, scientists spent decades seeking evidence, with little success. Then in 2001 and 2002, researchers at New Mexico Institute of Mining and Technology, the University of Florida and Florida Tech reported solid confirmation that lightning does indeed produce large quantities of X-rays. Scientists worldwide have been seeking to understand and explain the phenomenon since then, Uman said.

The New Mexico Tech researchers detected high-energy radiation from natural lightning. The UF/FIT’s International Center for Lightning Research Laboratory, located on a military base in Clay County, triggers lightning using wire-trailing rockets fired into passing storm clouds. In 2002, Uman’s team showed “triggered lightning” produces X-rays.

In the latest research, electrical engineering doctoral student Joey Howard, the paper’s lead author, and other UF/FIT researchers used a series of electric field detectors and sodium iodide X-ray detectors to try to probe X-rays more closely.

In the 2002 paper, the UF/FIT researchers confirmed that X-rays are produced by the stepped leader in natural lightning. In the latest paper, they narrowed the production of X-rays to the beginning of each step of the step leader, based on data gathered from one natural lightning strike and one triggered strike, Uman said.

“We could see when the electric field arrived at the sequence of stations, and it was the same with the X-rays,” Uman said. “We then went back and calculated what the source location was for the field and the X-ray.”

Dwyer said the research is one more step toward using X-rays to understand how lightning travels.

“A spark that begins inside a thunderstorm somehow manages to travel many miles to the ground, where it can hurt people and damage property,” he said. “Now, for the first time, we can actually detect lightning moving toward the ground using X-rays. So just as medical X-rays provide doctors with a clearer view inside patients, X-rays allow us to probe parts of the lightning that are otherwise very difficult to measure.”

Uman said the research will continue with more expensive, faster and more sensitive X-ray detectors. One area of future interest, he said, is whether lightning strikes to airplanes could produce X-rays harmful to passengers.


Story Source:

The above story is based on materials provided by University of Florida. Note: Materials may be edited for content and length.


Cite This Page:

University of Florida. "Scientists Close In On Source Of X-rays In Lightning." ScienceDaily. ScienceDaily, 16 July 2008. <www.sciencedaily.com/releases/2008/07/080715152322.htm>.
University of Florida. (2008, July 16). Scientists Close In On Source Of X-rays In Lightning. ScienceDaily. Retrieved July 31, 2014 from www.sciencedaily.com/releases/2008/07/080715152322.htm
University of Florida. "Scientists Close In On Source Of X-rays In Lightning." ScienceDaily. www.sciencedaily.com/releases/2008/07/080715152322.htm (accessed July 31, 2014).

Share This




More Earth & Climate News

Thursday, July 31, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Visitors Feel Part of the Pack at Wolf Preserve

Visitors Feel Part of the Pack at Wolf Preserve

AP (July 31, 2014) — Seacrest Wolf Preserve on the northern Florida panhandle allows more than 10,000 visitors each year to get up close and personal with Arctic and British Columbian Wolves. (July 31) Video provided by AP
Powered by NewsLook.com
Florida Panther Rebound Upsets Ranchers

Florida Panther Rebound Upsets Ranchers

AP (July 31, 2014) — With Florida's panther population rebounding, some ranchers complain the protected predators are once again killing their calves. (July 31) Video provided by AP
Powered by NewsLook.com
Big Waves In Arctic Ocean Threaten Polar Ice

Big Waves In Arctic Ocean Threaten Polar Ice

Newsy (July 30, 2014) — Big waves in parts of the Arctic Ocean are unprecedented, mainly because they used to be covered in ice. Video provided by Newsy
Powered by NewsLook.com
Raw: Thousands Flocking to German Crop Circle

Raw: Thousands Flocking to German Crop Circle

AP (July 30, 2014) — Thousands of people are trekking to a Bavarian farmer's field to check out a mysterious set of crop circles. (July 30) Video provided by AP
Powered by NewsLook.com

Search ScienceDaily

Number of stories in archives: 140,361

Find with keyword(s):
 
Enter a keyword or phrase to search ScienceDaily for related topics and research stories.

Save/Print:
Share:  

Breaking News:
from the past week

In Other News

... from NewsDaily.com

Science News

Health News

    Environment News

    Technology News



      Save/Print:
      Share:  

      Free Subscriptions


      Get the latest science news with ScienceDaily's free email newsletters, updated daily and weekly. Or view hourly updated newsfeeds in your RSS reader:

      Get Social & Mobile


      Keep up to date with the latest news from ScienceDaily via social networks and mobile apps:

      Have Feedback?


      Tell us what you think of ScienceDaily -- we welcome both positive and negative comments. Have any problems using the site? Questions?
      Mobile iPhone Android Web
      Follow Facebook Twitter Google+
      Subscribe RSS Feeds Email Newsletters
      Latest Headlines Health & Medicine Mind & Brain Space & Time Matter & Energy Computers & Math Plants & Animals Earth & Climate Fossils & Ruins