In 2019 sprite observations appeared on You-Tube showing green emissions in the top of some sprites and after the main sprite. The emissions were named green ghosts. We present here similar color camera observations made on 24 and 25 May 2020 from Lamy, NM. The recordings were made at 30 fps. The green ghost increased in brightness for 3 to 4 frames after the main ‘jellyfish’ sprite and decayed thereafter. The delayed green emissions are likely from atomic oxygen at 557.7 nm, the auroral green line, which is a forbidden atomic oxygen emission with a radiative life time of 0.7 s. In the atmosphere the emissions are affected by quenching and at the altitude of the green ghost the decay time constant is substantially less. We suggest that the green ghost is generated by super thermal electrons exciting ambient atomic oxygen (only 4.1 eV required). The electrons are energized by the large-scale sprite electric field, which initially caused the sprite, and decays over some time after the sprite. We present a simple model based on this idea. The model assumes an exponentially decaying sprite E-field and reproduces the observed delayed peak in the green emissions and the subsequent decay of the emissions.

We present our results on the second year of TOTO-Cheyenne (TGFs On Top Of Cheyenne), a continuing collaboration of the US Air Force Academy and the Naval Research Laboratory. The project’s goal is to study the ionizing radiation as lightning strikes near the antenna farm on the top of Cheyenne Mountain, near Colorado Springs CO. Thunderstorms and accompanying lightning produce ionizing radiation on time scales from milliseconds to minutes. This radiation includes terrestrial gamma-ray flashes, hard X-rays from stepped leaders, gamma-ray glows, and thunderstorm ground enhancements. Recent measurements indicate that getting up close and personal with the storms might produce more details about the complex processes inside. The US Rocky Mountains offer the opportunity to do just that by getting closer to the charge layers. This year’s experiment (starting in May 2019 and continuing to October 2019) involved the setup of a high speed camera at the Air Force Academy facing south to watch Cheyenne Mountain plus the reinstallation of a small gamma-ray and X-ray detection system (NaI and plastic scintillators) on the mountain. This year has proven to be a very active storm year. As of 20 July, there were already 25 strikes within 2 km of the detector (compared to 1 strike during the summer 2018).