<http://schema.org/articleBody>
"  When Corrado Cimarelli and Ulrich Kueppers were working on their experimental volcano, they weren&amp;#039;t expecting the plume to contain lightning. But they managed to capture their experiment creating its own electrical discharges, the first time that phenomenon has ever been seen in a lab. Their jet of highly pressurized gas and ash mimics the behavior of a natural volcanic plume, albeit on a much smaller and more contained scale. The scientists had been conducting experiments with this particular setup for years, and no one had noticed anything particularly shocking. That is, until one day when the team began to look at the plume using a high-speed camera. As they were watching, a strange flash of white, nearly imperceptible, appeared on the screen. &amp;quot;[At first] our colleague, Miguel, thought it might be a problem with the movie,&amp;quot; Kueppers says. The white flash repeated, though, and the team in Munich decided to take a closer look. And that&amp;#039;s when they saw lightning: Small 7-centimeter-long lightning bolts crackled along the sides, just like the much larger bolts that emerge from ash clouds during volcanic eruptions. &amp;quot;This is proof that what we&amp;#039;re doing is close to reality,&amp;quot; Kueppers says. Volcanic lightning is a poorly understood phenomenon that occurs in the ash cloud above certain volcanic eruptions. It makes for stunning pictures, and has even been observed to have a greenish hue in particular situations. The lab wasn&amp;#039;t looking to recreate this lighting, only to study the behavior of volcanic ash plumes under controlled conditions in the lab. For years the researchers at Ludwig Maximilian University of Munich have been creating experiments that accurately reproduced how volcanic eruptions behaved in the field, giving scientists a chance to make careful observations of volcanic phenomena under controlled conditions. &amp;quot;You want to be sure to control what is happening, and be sure to catch it when it does,&amp;quot; Cimarelli says.      The experiment itself involves a 1-inch narrow tube that shoots a mixture of argon gas and ash into a larger tank. The mixture of gas and ash is pressurized at a level of 10 megapascals, or about 100 times standard atmospheric pressure. When it gets shot into the tank, high-speed cameras and sophisticated sensors record everything that happens. Cimarelli, a geoscientist, had never studied lightning before, but learned about the subject, buying books and consulting with experts in the field as he, Kueppers, and their colleagues continued to run experiments, looking at lightning formation in different types of ash erupted from volcanoes all over the world. Using ash erupted from volcanoes in Mexico, Iceland, and the Caribbean, they found that heat was not a necessary component for creating the charged particles because their experiments were conducted at room temperature and still produced bright, crackling bolts as the mixture of ash and argon gas was forced through the tube. &amp;quot;We know that many mechanisms do the same thing at room temperature as high temperature, and many sensors are much happier at room temperature,&amp;quot; Kueppers says. The researchers found that the smaller ash particles actually produced more discharges than ash with larger particles. But the most exciting result of their experiments was perhaps the fact that there was lightning at all. In previous lab-based lightning experiments, lightning was induced in the lab by applying charged currents to the experiment in question, but here the small particles were all overachievers who managed to charge themselves. The process, known as triboelectrification, involves solids charging themselves due to friction, in this case clusters of ash particles rubbing against each other to create the charge. &amp;quot;This is the first time we can observe electrical discharge created by self-charging particles,&amp;quot; Cimarelli says. Lab-created lightning from self-charging particles is exciting enough, but there could be other applications for this research beyond volcanic lightning. The researchers think that their work could be applied to lightning associated with dust storms, planetary processes on other planets, or even industrial applications for industries that use a lot of small particles or granules in their manufacturing processes. "^^<http://www.w3.org/2001/XMLSchema#string>
<http://www.popularmechanics.com/science/environment/a9885/how-to-stir-up-volcanic-lightning-in-a-lab-16266258/>