Transient luminous events (TLEs) are electric discharges that occur above thunderclouds and have been categorized into several classes: elves, halos, sprites, and jets. Sprites and halos are TLEs caused by a similar mechanism, and they can occur together as a pair or separately. Sprites form above strong positive cloud-to-ground lightning strikes. The lightning strike forms a quasi-static electric field that accelerates electrons in the mid-atmosphere [Barrington-Leigh et al., 2001]. The result is an ionization wave, called a streamer that propagates downward at speeds up to ten percent the speed of light. Halos are relatively homogenous optical emission in the shape of a pancake. During a summer campaign in 2008, Stenbaek-Nielson and McHarg captured TLEs at 10,000 frames per second using two Phantom 7 imagers [Stenbaek‐Nielsen et al., 2010] On July 4, a halo and sprite were captured outside Socorro, New Mexico containing a unique wave structure within the halo. The structure could be a gravity wave travelling through the mesosphere. This gravity wave could be the secondary cause of sprite streamer formation
Morrison, Michael; Kosar, Burcu; and Spiva, Nicholas, "Measuring Unique Structures Within Sprite Halos" (2015). Aerospace, Physics, and Space Science Student Publications. 19.