Upward flashes triggering mechanisms

Upward flashes can be self-initiated or triggered-initiated. Locations where the tall structures are installed may present only triggering initiated upward flashes, only self-initiated or even both types of upward flashes. Upward flashes that were observed in Sao Paulo and Rapid City were all triggered-initiated by previous activity. This paper will present three triggering components of the triggering flash that provide the conditions necessary for the upward leader initiates based in optical and LMA observations.