Similarities in the Initiation of Upward Positive and Downward Negative Lightning Flashes

Similarities in the Initiation of Upward Positive and Downward Negative Lightning Flashes | Research Square window.SnipcartSettings = { analytics: { enabled: false } }; (function() { var accessVector = localStorage.getItem('access_vector') || ''; window.dataLayer = window.dataLayer || []; if (accessVector) { window.dataLayer.push({ user: { profile: { profileInfo: { snid: accessVector } } } }); } })(); (function(w,d,s,l,i){w[l]=w[l]||[];w[l].push({'gtm.start':new Date().getTime(),event:'gtm.js'});var f=d.getElementsByTagName(s)[0],j=d.createElement(s),dl=l!='dataLayer'?'&l='+l:'';j.async=true;j.src='https://www.googletagmanager.com/gtm.js?id='+i+dl;f.parentNode.insertBefore(j,f);})(window,document,'script','dataLayer','GTM-K279D39R'); Browse Preprints In Review Journals COVID-19 Preprints AJE Video Bytes Research Tools Research Promotion AJE Professional Editing AJE Rubriq About Preprint Platform In Review Editorial Policies Our Team Advisory Board Help Center Sign In Submit a Preprint Cite Share Download PDF Article Similarities in the Initiation of Upward Positive and Downward Negative Lightning Flashes Toma Oregel-Chaumont, Mohammad Azadifar, Antonio Šunjerga, Marcos Rubinstein, and 1 more This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-7713977/v1 This work is licensed under a CC BY 4.0 License Status: Posted Version 1 posted You are reading this latest preprint version Abstract This study examines the relationship between upward negative stepped leader pulses in upward positive lightning and preliminary breakdown pulses (PBPs) in downward negative lightning discharges. Through analysis of simultaneous channel-base current and electric field data from the Säntis tower in Switzerland, we found notable similarities between Category A and B upward positive lightning pulses and the “Classical” and “Narrow” PBPs observed in downward negative flashes. Statistical comparisons reveal correlations between electric field and current parameters for Category A pulses, supporting the field–current relationship for preliminary breakdown proposed in previous studies. These results suggest common physical mechanisms underlying both upward and downward lightning initiation processes, providing valuable insights into lightning initiation that could not be obtained from conventional field measurements alone. Furthermore, high-speed camera footage revealed that Category B pulses can be produced by a downward-propagating recoil leader. As a whole, these findings demonstrate that detailed observations of upward lightning can offer valuable insight into the complex processes underlying lightning initiation and propagation. Earth and environmental sciences/Natural hazards Physical sciences/Physics preliminary breakdown pulses lightning initiation electric field measurements S¨antis tower upward lightning Full Text Additional Declarations No competing interests reported. Cite Share Download PDF Status: Posted Version 1 posted You are reading this latest preprint version Research Square lets you share your work early, gain feedback from the community, and start making changes to your manuscript prior to peer review in a journal. As a division of Research Square Company, we’re committed to making research communication faster, fairer, and more useful. We do this by developing innovative software and high quality services for the global research community. Our growing team is made up of researchers and industry professionals working together to solve the most critical problems facing scientific publishing. Also discoverable on Platform About Our Team In Review Editorial Policies Advisory Board Help Center Resources Author Services Accessibility API Access RSS feed Manage Cookie Preferences © Research Square 2026 | ISSN 2693-5015 (online) Privacy Policy Terms of Service Do Not Sell My Personal Information {"props":{"pageProps":{"initialData":{"identity":"rs-7713977","acceptedTermsAndConditions":true,"allowDirectSubmit":true,"archivedVersions":[],"articleType":"Article","associatedPublications":[],"authors":[{"id":531479030,"identity":"6668289c-3a6e-448d-9627-e0710764554b","order_by":0,"name":"Toma Oregel-Chaumont","email":"data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAZAAAAAyAQMAAABI0h/eAAAABlBMVEX///8AAABVwtN+AAAACXBIWXMAAA7EAAAOxAGVKw4bAAAA20lEQVRIiWNgGAWjYPCCA1C6goGBvZ2BgRmfWh4ULQfOAEUOk6TlYBsRWuzZuxM/MNTckTe4dvjY44/zbPJ4mBkYPxfgs4Xn7GYJhmPPDDfcTks3OLgtrRiohVl6Bj4tErkbJBgbDjNuuJ1jJnFw2+HE/cwMbMw8+LVs/gHUYg/RMud/Yg8RWraBbEmEaGk4QISWM2e3WSQcO5w883ZamsSZY8lAvzA2S+PTwt7eu/nGh5rDtn23k49JVNTY5fGwNx/8jE8LGCSgshkbCGnArX0UjIJRMApGARgAAJ8PTW9PLeCYAAAAAElFTkSuQmCC","orcid":"","institution":"Swiss Federal Institute of Technology (EPFL)","correspondingAuthor":true,"prefix":"","firstName":"Toma","middleName":"","lastName":"Oregel-Chaumont","suffix":""},{"id":531479033,"identity":"05948bd4-17d1-430a-97ea-1a116f317d91","order_by":1,"name":"Mohammad Azadifar","email":"","orcid":"","institution":"Swiss Federal Institute of Technology (EPFL)","correspondingAuthor":false,"prefix":"","firstName":"Mohammad","middleName":"","lastName":"Azadifar","suffix":""},{"id":531479035,"identity":"d4925dd7-c0c0-4732-873e-595ffa4764f1","order_by":2,"name":"Antonio Šunjerga","email":"","orcid":"","institution":"University of Split","correspondingAuthor":false,"prefix":"","firstName":"Antonio","middleName":"","lastName":"Šunjerga","suffix":""},{"id":531479036,"identity":"dee42e45-f25c-4546-b78c-7baf06e1d8ad","order_by":3,"name":"Marcos Rubinstein","email":"","orcid":"","institution":"HEIG, University of Applied Sciences and Arts Western Switzerland","correspondingAuthor":false,"prefix":"","firstName":"Marcos","middleName":"","lastName":"Rubinstein","suffix":""},{"id":531479038,"identity":"6481621d-f899-4352-8d04-993af8e81141","order_by":4,"name":"Farhad Rachidi","email":"","orcid":"","institution":"Swiss Federal Institute of Technology (EPFL)","correspondingAuthor":false,"prefix":"","firstName":"Farhad","middleName":"","lastName":"Rachidi","suffix":""}],"badges":[],"createdAt":"2025-09-25 14:23:44","currentVersionCode":1,"declarations":"","doi":"10.21203/rs.3.rs-7713977/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-7713977/v1","draftVersion":[],"editorialEvents":[],"editorialNote":"","failedWorkflow":false,"files":[{"id":93920739,"identity":"fed8c0dd-d560-47f2-9723-2e7e157dcfb2","added_by":"auto","created_at":"2025-10-20 09:40:08","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"acdc-reference","size":17399080,"visible":true,"origin":"","legend":"","description":"","filename":"OC2025bmanuscriptV2.pdf","url":"https://assets-eu.researchsquare.com/files/rs-7713977/v1/c052e54c39dd521a116ab7d9.pdf"},{"id":93920738,"identity":"50599daf-bbf8-4b25-9a2d-c97198933e7d","added_by":"auto","created_at":"2025-10-20 09:40:08","extension":"json","order_by":1,"title":"","display":"","copyAsset":false,"role":"acdc-reference","size":7057,"visible":true,"origin":"","legend":"","description":"","filename":"d241bb9e59ca44dd9eb2c544eb46c986.json","url":"https://assets-eu.researchsquare.com/files/rs-7713977/v1/586afc853a1c95df8e58062a.json"},{"id":97895472,"identity":"261ae153-2ca1-403c-ab9e-4f0612efd762","added_by":"auto","created_at":"2025-12-10 15:34:17","extension":"pdf","order_by":1,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":16411159,"visible":true,"origin":"","legend":"","description":"","filename":"OC2025bmanuscriptV2.pdf","url":"https://assets-eu.researchsquare.com/files/rs-7713977/v1_covered_014923dd-cae9-483a-a38a-5400b369ddea.pdf"}],"financialInterests":"No competing interests reported.","formattedTitle":"Similarities in the Initiation of Upward Positive and Downward Negative Lightning Flashes","fulltext":[],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":false,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":false,"hideJournal":true,"highlight":"","institution":"","isAcceptedByJournal":false,"isAuthorSuppliedPdf":true,"isDeskRejected":"","isHiddenFromSearch":false,"isInQc":false,"isInWorkflow":false,"isPdf":true,"isPdfUpToDate":true,"isWithdrawnOrRetracted":false,"journal":{"display":true,"email":"[email protected]","identity":"researchsquare","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":true,"externalIdentity":"","sideBox":"","snPcode":"","submissionUrl":"/submission","title":"Research Square","twitterHandle":"researchsquare","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"","reportingPortfolio":"","inReviewEnabled":false,"inReviewRevisionsEnabled":true},"keywords":"preliminary breakdown pulses, lightning initiation, electric field measurements, S¨antis tower, upward lightning","lastPublishedDoi":"10.21203/rs.3.rs-7713977/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-7713977/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"This study examines the relationship between upward negative stepped leader pulses in upward positive lightning and preliminary breakdown pulses (PBPs) in downward negative lightning discharges. Through analysis of simultaneous channel-base current and electric field data from the Säntis tower in Switzerland, we found notable similarities between Category A and B upward positive lightning pulses and the “Classical” and “Narrow” PBPs observed in downward negative flashes. Statistical comparisons reveal correlations between electric field and current parameters for Category A pulses, supporting the field–current relationship for preliminary breakdown proposed in previous studies. These results suggest common physical mechanisms underlying both upward and downward lightning initiation processes, providing valuable insights into lightning initiation that could not be obtained from conventional field measurements alone. Furthermore, high-speed camera footage revealed that Category B pulses can be produced by a downward-propagating recoil leader. As a whole, these findings demonstrate that detailed observations of upward lightning can offer valuable insight into the complex processes underlying lightning initiation and propagation.","manuscriptTitle":"Similarities in the Initiation of Upward Positive and Downward Negative Lightning Flashes","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2025-10-20 09:40:03","doi":"10.21203/rs.3.rs-7713977/v1","editorialEvents":[{"type":"communityComments","content":0}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"researchsquare","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":true,"externalIdentity":"","sideBox":"","snPcode":"","submissionUrl":"/submission","title":"Research Square","twitterHandle":"researchsquare","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"","reportingPortfolio":"","inReviewEnabled":false,"inReviewRevisionsEnabled":true}}],"origin":"","ownerIdentity":"8d1a5f62-c690-4f80-9f25-5ed360fd18c5","owner":[],"postedDate":"October 20th, 2025","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"posted","subjectAreas":[{"id":56505014,"name":"Earth and environmental sciences/Natural hazards"},{"id":56505015,"name":"Physical sciences/Physics"}],"tags":[],"updatedAt":"2025-12-08T14:23:45+00:00","versionOfRecord":[],"versionCreatedAt":"2025-10-20 09:40:03","video":"","vorDoi":"","vorDoiUrl":"","workflowStages":[]},"version":"v1","identity":"rs-7713977","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-7713977","identity":"rs-7713977","version":["v1"]},"buildId":"XKTyCvWXoU3ODBz1xrDgd","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}