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Who's Afraid of Dark Lightning and Should You Be?

Thu, 2013-04-11 11:11 -- llancaster
Apr 11 2013 - 11:00am
By: Emilie Lorditch
Credit: University Corporation for Atmospheric Research

A newly recognized kind of electrical discharge from inside thunderstorms that produces X-rays and gamma rays but little visible light, called dark lightning, was the subject of a press conference held on April 10, 2013 during the European Geosciences Union General Assembly meeting in Vienna, Austria.

Joseph Dwyer, a professor of physics and space sciences at the Florida Institute of Technology in the USA, explained the "dark side" of dark lightning.  
"In the 1990s spacecraft that was designed to measure X-rays and gamma rays in space were measuring these powerful gamma ray bursts coming from the Earth's atmosphere," said Dwyer.  "Researchers initially thought these bursts were coming from high in the atmosphere and did not consider them to be a radiation hazard."
Over time, the origin of these gamma ray bursts was discovered to be deep within thunderstorms, which could pose a radiation risk for airplane passengers.   Dwyer explained how advances in computer modeling have finally solved the mystery as to how a thunderstorm could generate powerful gamma rays.   
"A large number of energetic electrons and the anti-matter equivalent, positrons, are created causing a chain reaction inside the thunderstorm," said Dwyer.  "This causes a large spasm of energetic particles that collapses the electric field inside the storm, producing these bursts of gamma rays creating a lot of radiation."
Even with the large dose of radiation created from the thunderstorm, Dwyer clarified that the risk of exposure is still low.  "According to the models, people inside an aircraft struck by dark lighting struck at the right place at the right time could receive a sizeable dose of radiation, comparable to a full-body CT scan, but the probability of this happening is probably small," said Dwyer.  "I'm a very overprotective parent and I would not worry about flying with my kids; this is not a reason to avoid flying."  
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