{"id":3793,"date":"2019-05-22T17:37:47","date_gmt":"2019-05-22T15:37:47","guid":{"rendered":"http:\/\/junq.info\/?p=3793"},"modified":"2019-07-22T17:42:18","modified_gmt":"2019-07-22T15:42:18","slug":"how-does-a-lightning-bolt-find-its-target","status":"publish","type":"post","link":"https:\/\/junq.info\/?p=3793","title":{"rendered":"How does a lightning bolt find its target?"},"content":{"rendered":"\n

Once, thunderstorms with thunder and\nlightning were interpreted as signs of the god\u2019s wrath; nowadays, we are taught\nthe mechanics behind a thunderstorm in school. You are probably already\nthinking about ice crystals that are smashed together by strong winds inside\nclouds, creating static charges in the process. How does a lightning bolt,\nthough, find its way from the cloud to the ground? This question still keeps\nscientists awake at night \u2013 and there is still not a clear answer to how\nexactly the formation and movement of a lightning bolt work. This Question of\nthe Month will give a brief summary on how a lightning bolt selects its target.<\/p>\n\n\n\n

Lightning [1,2] occurs always when a large\nthunderstorm cloud with strong winds generates sufficient electrostatic charge that\nit must discharge towards the ground. The discharge itself occurs (simplified)\nin a twostep process, consisting of a main lightning bold and a preflash: The\npreflash travels as comparably weak (but still dangerous!) current downwards\nfrom the cloud. This usually happens in little jumps, which have been\ninvestigated with high-speed cameras. They show that the current path is\napparently selected randomly by slowing down at a given position and then\nrandomly selecting the next to jump to. This random selection appears to happen\nwithin a sphere of a few tens of meters in diameter around the tip of the\ngrowing lightning bolt. The process also involves growing many tendrils with\nindividual tips and thus covers a large area (see also Fig. 1). With this\nprocedure, the lightning bold eventually \u201cfeels\u201d its way to the ground until it\nreaches it either directly or via a structure connected to it.<\/p>\n\n\n\n

\"\"
Figure 1: Lightning bolts are branching off into many tendrils. [3] <\/figcaption><\/figure><\/div>\n\n\n\n

Therefore, if a conductive object reaches\ninto such a sphere, the bolt will immediately jump to it and use it as a\nlow-resistance shortcut to the ground \u2013 as a result, if possible, shortening\nthe path for the discharge. This behavior leads to the curious effect of\nexclusion areas around structures that are protected with lightning rods, in\nwhich practically no ground strike will occur, and a person will not be hit\ndirectly. Unfortunately, this will not completely protect the person, as the\nelectricity can still be dangerous within the ground.<\/p>\n\n\n\n

Now that the preflash has found a path to\nthe ground, the second phase starts, and the majority of the charge starts to\nflow with up to 20 000 A along the path found by the preflash. This is also the\nportion of the discharge that is visible by bare eye. It can consist of several\ndistinct discharges that all follow the path of ionized air of the previous one,\ncreating the characteristic flickering of a lightning bolt. <\/p>\n\n\n\n

How the entire process from preflash to\nmain discharge works is still not completely understood today and much of the\npresented insights were simply gathered phenomenologically by camera imaging.\nAdditionally, there are many more types of and effects related to lightning\nbolts, which are relevant for our understanding of a variety of weather\nphenomena. All in all, thunderstorms are still something magical today, even if\nonly figuratively.<\/p>\n\n\n\n

— Kai Litzius<\/p>\n\n\n\n

Further reading:<\/p>\n\n\n\n

\n[1] http:\/\/stormhighway.com\/cgdesc.php#part1\n\n<\/p>\n\n\n\n

[2] https:\/\/what-if.xkcd.com\/16\/<\/p>\n\n\n\n

[3] https:\/\/commons.wikimedia.org\/wiki\/File:Lightning_over_Oradea_Romania_2.jpg<\/a><\/p>\n\n\n\n

[4] Chem. Unserer\nZeit, 2019, 53. DOI: 10.1002\/ciuz.201980045<\/p>\n","protected":false},"excerpt":{"rendered":"

Once, thunderstorms with thunder and lightning were interpreted as signs of the god\u2019s wrath; nowadays, we are taught the mechanics behind a thunderstorm in school. You are probably already thinking about ice crystals that are smashed together by strong winds inside clouds, creating static charges in the process. How does a lightning bolt, though, find… Read More »How does a lightning bolt find its target?<\/span><\/a><\/p>\n","protected":false},"author":12,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":true,"template":"","format":"standard","meta":{"neve_meta_sidebar":"","neve_meta_container":"","neve_meta_enable_content_width":"","neve_meta_content_width":0,"neve_meta_title_alignment":"","neve_meta_author_avatar":"","neve_post_elements_order":"","neve_meta_disable_header":"","neve_meta_disable_footer":"","neve_meta_disable_title":"","footnotes":""},"categories":[6,84],"tags":[],"aioseo_notices":[],"_links":{"self":[{"href":"https:\/\/junq.info\/index.php?rest_route=\/wp\/v2\/posts\/3793"}],"collection":[{"href":"https:\/\/junq.info\/index.php?rest_route=\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/junq.info\/index.php?rest_route=\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/junq.info\/index.php?rest_route=\/wp\/v2\/users\/12"}],"replies":[{"embeddable":true,"href":"https:\/\/junq.info\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=3793"}],"version-history":[{"count":2,"href":"https:\/\/junq.info\/index.php?rest_route=\/wp\/v2\/posts\/3793\/revisions"}],"predecessor-version":[{"id":3796,"href":"https:\/\/junq.info\/index.php?rest_route=\/wp\/v2\/posts\/3793\/revisions\/3796"}],"wp:attachment":[{"href":"https:\/\/junq.info\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=3793"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/junq.info\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=3793"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/junq.info\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=3793"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}