موسسه ژئوفیزیک دانشگاه تهرانفیزیک زمین و فضا2538-371X46420210120Effect of Earth’s Magnetic Field on Prerequisites for Lightning Initiation in ThunderstormEffect of Earth’s Magnetic Field on Prerequisites for Lightning Initiation in Thunderstorm1731887294210.22059/jesphys.2019.279456.1007108FABabakSadeghiPh.D. Student, School of Electrical and Computer Engineering, Faculty of Engineering, University of Tehran, IranFarahnazTaghaviAssistant Professor, Department of Space Physics, Institute of Geophysics, University of Tehran, Tehran, Iran0000-0003-4399-882XAmir AbbasShayegani AkmalAssistant Professor, School of Electrical and Computer Engineering, Faculty of Engineering, University of Tehran, IranJournal Article20190422In this study, a hypothesis is proposed about the possible effect of Earth’s magnetic field (EMF) on the charge structure of thundercloud based on the Lorentz force equation. To prove this hypothesis, a simulation using the 12<sup>th</sup> International Geomagnetic Reference Field (IGRF) model has been conducted. In this simulation, three scenarios are considered based on updrafts/downdrafts categories of the charge motion to analyze how a change in velocity of hydrometeor could influence the charge structure of a thunderstorm. The results of simulations show that by stronger velocities, the charged hydrometeors will experience higher amounts of magnetic force. In fact, after cloud electrification and creation of individual charged hydrometeors, Earth’s magnetic force could push the separated charges. Therefore, the distance between separated charges will increase more and more, that leads to the collection of the same sign charges in some layers, which are called charge layers of thunderclouds. Consequently, the probability of electric field and lightning initiation will increase. Finally, results indicate that the effect of EMF on charged hydrometeors might be one of the mechanisms of forming thundercloud’s charge structure and lightning initiation.In this study, a hypothesis is proposed about the possible effect of Earth’s magnetic field (EMF) on the charge structure of thundercloud based on the Lorentz force equation. To prove this hypothesis, a simulation using the 12<sup>th</sup> International Geomagnetic Reference Field (IGRF) model has been conducted. In this simulation, three scenarios are considered based on updrafts/downdrafts categories of the charge motion to analyze how a change in velocity of hydrometeor could influence the charge structure of a thunderstorm. The results of simulations show that by stronger velocities, the charged hydrometeors will experience higher amounts of magnetic force. In fact, after cloud electrification and creation of individual charged hydrometeors, Earth’s magnetic force could push the separated charges. Therefore, the distance between separated charges will increase more and more, that leads to the collection of the same sign charges in some layers, which are called charge layers of thunderclouds. Consequently, the probability of electric field and lightning initiation will increase. Finally, results indicate that the effect of EMF on charged hydrometeors might be one of the mechanisms of forming thundercloud’s charge structure and lightning initiation.https://jesphys.ut.ac.ir/article_72942_ff3aa90735f7e9a83c7ea46e6c7e7a47.pdf