Black hole power in a lightning bolt

Have you ever been on a plane during a thunderstorm that experienced a direct lightning strike? While most commercial airliner will do their best to avoid thunderclouds delivering the wrath of the atmosphere, it's estimated that every plane in the U.S. is struck more than once per year.

Large commercial planes are equipped to route the electrical current from a lightning strike so that it avoids sensitive electronics, and most passengers may not even realize that a plane has been struck when it does occur. However, the electrical current and loud clap of thunder are not all that is produced by a bolt of lightning. It's only within the past 20 years that research has confirmed that lightning also emits x-rays and gamma-rays.

One source of x-rays is normal lightning, under normal atmospheric pressure that occurs near the ground. These x-rays are measured at strengths analogous to the energy range commonly emitted by CT scanning devices used in the health care industry. Then there are gamma-rays, high energy x-rays usually seen emitted by particle accelerators, exploding stars, and black holes, that have been detected as a continuous kind of glow within clouds. Additionally, a separate class of gamma-rays, called terrestrial gamma-ray flashes or TGFs, are even more powerful, brief bursts that can be seen by spacecraft and satellites in low earth orbit. TGFs are the most energetic phenomena on the planet, and are thought to be caused by intracloud lightning (lightning that occurs between clouds). TGFs appear all over the world where there are thunderstorms, but nobody understands exactly why or how.

Scientists at the University of Alabama in Huntsville reported in a press conference today at the 2014 American Geophysical Union that they have been delving into the world of these high energy particles associated with the  bursts of light, and have concluded that these TGFs can be produced by any type of storm from the "garden variety" to more extreme events. That weaker or moderate strength storms would produce TGFs was totally unexpected based on earlier theories.

While lightning strikes some 50 times per second around the globe, TGFs fire up to 1100 times per day based on data from NASA's FERMI Gamma-ray Burst Monitor (GBM). Separation of positive and negative charges between layer in the clouds leads to lighting, and sometimes when lighting does fire a surge of electrons is deflected upward. Those energetic electrons cause gamma ray flashes when they bump into other particles in the atmosphere. The TGFs that are measured by craft in low-earth orbit like NASA's FERMI GBM form between 7-9 miles high, but TGFs are likely to form at lower altitudes well. Although, because of attenuation in the atmosphere those at lower altitude are harder to detect from space, so the total numbers of TGFs are probably vastly underestimated.

In order to address this issue, researchers attempted a gutsy experiment in which they actually flew an Airbus plane into a thunderstorm. The plane was equipped with a system called ILDAS to measure various properties of lightning strikes. The plane entered the thunderstorm to measure the radiation coming from the storm at approximately 10,000 feet, and over five hours experienced extreme turbulence and more than 20 direct lightning strikes. The data from the flight corroborates previous ground-based measurements linking gamma-rays and x-rays to lightning strikes. As long as there are enough brave pilots, this type of in-storm research will be one way that the scientists can get a better understanding of lower altitude TGFs.

There are many questions remaining about how and why these high energy particles are produced by storms, and how they influence other atmospheric phenomena. What we do know now is that x-rays and gamma-rays that are detected can be tracked back to their source, the lightning, to help us learn more about the dangerous, dramatic, and mesmerizing flashes of light.

Lightning strike photo

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Lightning caught in the act by BB pal Scott Matthews on Captiva Island, Florida, looking west over the Gulf of Mexico.

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Video of moving truck struck by lighting

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A moving truck is struck by lightning in Alberta, Canada. The couple inside were rescued by police, according to ABC News.

Pope resigns, God strikes St. Peter's Basilica with lightning

NewImage Just hours after Pope Benedict XVI quit, a lightning bolt struck St. Peter's Basilica in the Vatican. Yeah, yeah, lightning probably strikes the church on days when the pope hasn't resigned too. But it's more fun to ignore that as you appreciate this. (The Guardian)

A practical use for volcanic lightning (besides metal album covers)

Here's a story that combines two favorite bits of volcano news into one interesting discovery. You know those great, freaky photos of volcanic lightning? (In case you don't, I've got one posted above.) Remember how the Icelandic volcanic eruptions totally screwed up everybody's airplane travel plans?

Apparently, studying volcanic lightning could lead to better eruption detection systems that could make it easier to predict how big a plume of ash off that volcano will be—knowledge that can help airlines and travelers be better prepared. At Nature, Richard Monastersky reports:

The researchers found that the amount of lightning correlated with the height of the plume, something they could not test using more limited data collected during an eruption at Alaska’s Mount St Augustine in 2006. This observation is important, says Behnke, because systems to monitor lightning could provide an estimate for the size of an eruption, which is not always easy to assess for remote volcanoes.

During a previous eruption at Mount Redoubt in 1989 and 1990, for example, the size of the plume wasn’t known and a plane nearly crashed after passing through the ash cloud and temporarily losing all power from its engines. Behnke and her colleagues suggest that VHF stations similar to the ones they installed at Mount Redoubt could be used to monitor volcanoes to give early warning of an eruption and an estimate of its size.

Read the rest at Nature.com

Via Graham Farmelo

Image: Oliver Spalt via CC

Behold: The world's largest Tesla coil

Electrical engineer Greg Leyh built the giant Tesla coil in this video, and wants to construct an even larger version: Two 10-story-high towers that would send lightning zinging across an area the length of a football field. New Scientist interviewed Leyh, to find out what the point of this is (besides the obvious inherent awesomeness):

Lightning can break down air up to five times more easily than normal electric arcs [between two oppositely charged rods in the lab], using tricks we don't yet understand. However, recent theories and a few tantalising experimental results suggest that normal arcs start to gain lightning-like abilities once they grow past about 60 metres in length. If we can build a machine this large, we'll very quickly arrive at a better understanding of what's going on.

A couple of weeks ago, Pesco pointed out that you can actually donate money towards making this project happen. Double awesome!