Upward lightning from tall objects can be either self-initiated (SIUL), that is, leaders originating due to locally strong electric fields but without any preceding lightning, or triggered by prior lightning discharges in the general vicinity, termed lightning-triggered upward lightning (LTUL). The LTULs can be triggered by (1) nearby +CG return strokes propagating through previous leader networks near the tall object, or (2) the overhead proximity of horizontally propagating negative stepped leaders from either IC or +CGs. Examples of both modes of LTULs are presented. The meteorological environments in which LTULs occur in the U.S. high plains show a strong similarity to the convective regimes (trailing MCS stratiform regions) and the parent lightning which trigger sprites.
Redes Sociais