Lightning Emits X-Rays

Makarand writes "Scientists have now confirmed that lightning does emit X-rays according to this BBC News article. That lightning might emit high energy radiation was first suggested in 1925, however, confirmation had proven difficult because of the sporadic nature of lightning and the electromagnetic "noise" it generates. A team at the University of Florida built a special tower allowing them to study lightning in detail by firing rockets trailed by grounded wire into storm clouds to trigger strikes. They detected X-Ray bursts that typically lasted less than 100 microseconds. The breakdown of air by strong electrical fields when the lightning creates a path from clouds to ground may generate these X-rays."

Comments

The real source is

[Technician]

Just my humble opinion, but in an X-Ray tube, the X-Rays are produced when high speed electrons strike a hard target (tungston in the tube). I wonder if the X-rays do not originate from the lightning strike itself, but from the high current striking the metal (the wire) that has been added to the mix in their test. Any data on a strike minus the added metal?
My guess if a strike hits a radio tower, the only portion of the bolt generating X-rays is at the point of the electrons striking the metal tower (assuming cloud negative strike). Just a hunch. I could be completely off base on this one.

Re:The real source is

[DrFlounder]

The radiation from an X-ray tube is a special case of bremsstrahlung, or braking radiation, that occurs when a charged particle is accelerated (or decelerated). Often this happens when an energetic electron is decelerated by hitting metal, but anything that changes a electron's trajectory will cause it to radiate.

The real story here is not that X-rays are emitted, but that there are high energy electrons produced by lightning (called runaways because they gain more energy from the accelerating electric field than they lose from collisions with the background particles). Existing models of lightning don't predict the creation of these electrons. In this sense, it doesn't matter what caused the electrons to radiate. What matters is that electrons were created that had enough energy to produce the X-rays, which means that our models need to be corrected.