The Atmosphere-Space Interactions Monitor (ASIM) observatory has recorded five blue jets, an anomalous type of lightning that strikes from the top of a thundercloud into the stratosphere. This is reported in an article published in the journal Nature.
The 10 microsecond jets were spotted on February 26, 2019, off Nauru Island in the Pacific Ocean. One of the lightning flashes produced a jet that reached the stratopause – the boundary between the stratosphere and the ionosphere at an altitude of about 50 to 55 kilometers. In addition to the jets, “elves” (ELVES) were recorded, which are expanding rings of optical and ultraviolet radiation in the stratosphere, lasting no more than a millisecond.
Blue jets occur during electrical breakdown between a positively charged top of a thundercloud and a negatively charged layer of air above it. As a result, a leader is formed – a conducting channel of ionized air, through which the discharge propagates. However, in this case, the radiation from the leader was weak, which indicates that the leader itself was short compared to the conductive channels of conventional lightning.
Blue jets themselves refer to streamers – branched filaments of electrical discharges, similar to those generated by Tesla coils. In addition, blue jets are likely to occur more frequently than previously thought.