The scientific community's perception of the middle atmosphere above thunderstorms as “uninteresting” changed completely in the last decade. Today, a host of lightning-related Transient Luminous Events (TLEs) have been identified, including sprites, blue jets, elves, sprite halos, and trolls. Others may remain to be discovered.

Aside from the intrinsic scientific issues arising from this linkage of tropospheric electrical phenomena with that of middle atmosphere, a number of practical questions emerge. What, if any threats might TLEs pose to aerospace operations above 20 km? Do sprites represent a heretofore undocumented source of middle atmospheric Nox? What role might they play in the global electrical circuit, as well as in the energetics of the upper atmosphere [Bering et al., 1998]? Might these phenomena impact satellite-based global monitoring and surveillance efforts?