Electric field characteristics during a thunderstorm: A review of characteristics of electric field prior to lightning strike

Abstract

The study of electric field is an important tool for lightning research. Electric Field Mills (EFMs) are electromechanical devices used to observe static atmospheric electric fields during fair weather and during storm conditions. EFM readings show significant changes in electric field due to an approaching thunderstorm and particularly, during lightning periods. Attempts to comprehend the variations prior to and after a strike has been done by observatories all over the world. This paper focuses on identifying characteristic changes in atmospheric electric field prior to a lightning strike. Both static and dynamic field changes are studied by means of literature survey and static field variations are also studied through analysis of EFM data from Sonnblick Observatory, Austria and National Centre for Earth Science Studies (NCESS), Trivandrum, Kerala. During thunderstorms and the few seconds prior to lightning, significant changes are observed in both static and dynamic electric fields. Static field changes include a magnitude rise and reversal of direction of electric field from the fair weather situation, and dynamic field changes are characterized by the occurrence of Preliminary Breakdown Pulses(PBP) which is the dynamic electrical activity inside the cloud before a strike. This study, by identifying the characteristic changes in atmospheric electric field prior to lightning strike by comparing multiple observations from different parts of the world, points to great possibilities in the field of lightning prediction.