4/29/2023 0 Comments Thunder and lightning![]() Understanding why lightning proceeds in steps isn’t going to help us make it less dangerous. His team is now working on building a computational model of lightning to test whether the process they expect can explain the stepping behaviour. He and his student Alejandro Malagón‐Romero set out this hypothesis in 2019. Dr Luque wants to find out if this is right through his eLightning project. In the context of lightning, at lower altitudes, there are more air molecules and the attachment of electrons to them could work itself out in a slightly different way to produce the stepping pattern. This explanation is uncontroversial, says Dr Luque, but what we don’t know is whether – as he suspects – an analogous process could explain why lightning itself proceeds in steps. ‘People used to think that thunderstorms were rare … That was because we couldn’t see them.’ Prof. In some areas of the streamer, electrons attach to air molecules and this increases the strength of the electric field, producing brighter light. ![]() In sprites, the bright glowing is thanks to the behaviour of electrons, says Dr Luque. And as the streamers propagate, some spots within them glow more brightly and persistently. The channels in sprites are made of many tiny filaments called streamers. But Dr Luque says sprite discharge channels are ‘pretty much the same temperature as the surrounding air’. Lightning creates temperatures hotter than the surface of the sun. Though they are less familiar than lightning, the physics of sprites is easier to study because, at such high altitude, there is little air and so electric discharges happen more slowly and at colder temperatures. Dr Luque studied them mainly by looking at pictures taken by research aeroplanes. Their existence was doubted for years as they are hard to see from the ground. Sprites are huge, coloured jets of light that occur between 50 and 90 kilometres above the ground, far higher than thunderstorms. He says there are a few papers on this but essentially no accepted theories.ĭr Luque reckons he might have some insights into the problem, however, through his work studying an even more incredible yet better understood electric phenomenon – sprites. It pauses for a while at intervals before moving on, says Dr Alejandro Luque at the Institute of Astrophysics of Andalucía in Granada, Spain. If, for example, you were to film a lightning strike and play it back in super slow motion, you’d notice that the strike proceeds in steps. Researchers in the Netherlands have looked at the numbers of fires started by lightning in the forests of Alaska and Canada and found these have risen by 2% to 4% a year for the past 40 years. There are some indications that this might be happening already. In 2014, Professor David Romps at the University of California, Berkeley, US, developed an atmospheric model that predicted lightning will increase by 12% for every degree Earth warms. Lightning and thunderstorms appear to be getting more common and there are suggestions that this will continue as a result of global warming. Lightning might seem fairly rare, but it has happened about 700 times – we get about 100 strikes per second – somewhere around the globe in the time it has taken you to read this sentence. There almost always follows precipitation and strong gusty winds. ![]() Thunderstorms happen when a cloud forming in this way quickly grows very large, sucking in more and more water vapour. Many clouds form when warm wet air rises to high altitudes where it gets colder and condenses into water droplets.
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