Scientists Surprised by X-rays from Lab Lightning

Robert Roy Britt

Date: 31 October 2005 Time: 01:04 PM ET

We can all stop arguing about whether the climate is changing. Evidence is overwhelming, from shrinking glaciers to melting polar ice caps and seas rising at twice the rate of the pre-industrial era. Animals are changing migration and mating patterns; in the North, 125 lakes disappeared; river ice is melting sooner in spring. This year is expected to be the hottest, stormiest and driest on record. The big remaining question is how much of the trend is natural (scientists admitted they know little about the Sun's role!) and how much is exacerbated by greenhouse gas emissions. Meanwhile, a host of studies made dire predictions about the inevitability of rising temperatures and swamped coastlines over the next century. Nasty side effects were predicted: more intense rainstorms; worse droughts; stronger hurricanes; increased allergies; ice-free arctic summers; and economic costs. A couple novel solutions were proposed: altering airline flights and lofting a ring of miniature satellites to shade the equator. Tempers rose in 2005, too, with the year closing on a low note from the perspective of more than 150 nations who pledged to do something about the problem, without the support of the United States or China.
CREDIT:

Sparks created in a lab give off X-rays, scientists announced Monday.

X-rays are a byproduct of high-energy electron discharges in the Sun, in exploding stars, and even in lightning. Many scientists did not expect sparks alone to do the trick.

Researchers at Florida Institute of Technology brought their equipment, which had detected X-rays in lightning, into the lab. Half the team expected to see X-rays and the other half did not.

In sparks of 1.5 million to 2 million volts, the researchers indeed recorded X-rays that were remarkably similar to those produced by lightning.

"This amazed us. It opens the door to answering really big questions about lightning by generating it in the lab," said team member Hamid Rassoul. "It also tells us that we have a lot to learn about how even small sparks work."

X-rays are a form of electromagnetic radiation, on a spectrum that runs from radio waves on the low end to gamma rays on the high end and includes visible light, too.

Scientists don't know why lightning spawns X-rays. They theorize it involves a "runaway breakdown" of the air, in which electrons escape their normal bonds and gain very large energies.

"We didn't think [X-rays] could be made so easily in the air," said study leader Joseph Dwyer. "The results should allow for the detailed laboratory study of runaway breakdown, a mechanism that may play a role in thunderstorm electrification, lightning initiation and propagation, and terrestrial gamma-ray flashes."

The discovery is published in the journal Geophysical Research Letters.