beecee Posted March 20, 2019 Posted March 20, 2019 https://arstechnica.com/science/2019/03/thunderstorm-with-eye-popping-720gj-of-energy/ Thunderstorm with eye-popping 720GJ of energy Measured muon flux indicates thunderstorm reached a potential of 1.4GV. CHRIS LEE - 3/19/2019, 9:30 PM Nothing says "I love diving headfirst into a ditch" like your hair suddenly elevating to the tingly feel of electricity. Thunderstorms are amazing from inside a building, but they're scary if you're trapped outside. And, despite a good deal of observation, an element of mystery surrounds them. For instance, we know that lightning can produce free neutrons, antimatter, and gamma rays, but we don't have much idea of how that happens. That has partially changed thanks to an Indian muon telescope, called GRAPES-3—a classic example of a backronym. GRAPES-3 is designed to detect muons (a heavier cousin to the electron and positron) that are generated as gamma rays hit the Earth’s atmosphere. It is a relatively simple detector that has the benefit of covering a reasonable chunk of sky with good angular resolution. The detectors are also buried under a thick layer of concrete, so muons need to be quite energetic to get to them. Prediction: Lightning with a chance of telescopes: GRAPES-3 doesn’t actually care where the muons come from; it just happily counts away. Evidently, the scientists running the detector noticed that their data would always go a bit skewiff every time a thunderstorm passed over. Instead of ignoring this, the researchers (while keeping their heads low), installed a set of electric field monitors at various distances from the observatory and started logging electric field strength every time a storm passed over. That data could be easily compared to the muon detection rate. Unsurprisingly, storms are complex beasts, resulting in a lot of data that simply couldn’t be interpreted. Except for one storm. This is the story of that storm. more at link...... the paper: https://journals.aps.org/prl/abstract/10.1103/PhysRevLett.122.105101 Measurement of the Electrical Properties of a Thundercloud Through Muon Imaging by the GRAPES-3 Experiment ABSTRACT The GRAPES-3 muon telescope located in Ooty, India records rapid (∼10 min) variations in the muon intensity during major thunderstorms. Out of a total of 184 thunderstorms recorded during the interval of April 2011–December 2014, the one on December 1, 2014 produced a massive potential of 1.3 GV. The electric field measured by four well-separated (up to 6 km) monitors on the ground was used to help estimate some of the properties of this thundercloud, including its altitude and area that were found to be 11.4 km above mean sea level and ≥380 km2, respectively. A charging time of 6 min to reach 1.3 GV implied the delivery of a power of ≥2 GW by this thundercloud that was moving at a speed of ∼60 km h−1. This work possibly provides the first direct evidence for the generation of gigavolt potentials in thunderclouds that could also possibly explain the production of highest-energy (100 MeV) gamma rays in the terrestrial gamma-ray flashes.
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