Gigantic electrical discharges between thunderclouds and the ionosphere, observed by a team in Taiwan, represent a previously unrecognized form of lightning. Su Han-tzong and Hsu Rue-ron of National Cheng Kung University, and colleagues, have directly observed five gigantic jets extending from clouds about 16 km above the ground to the ionosphere at 90 km.

Initially, the team believed that the jets they recorded at the southern tip of Taiwan in July 2002 were a form of the so-called "blue jets" discovered by researchers in the US in 2001. However, detailed analysis revealed that the gigantic jets are a new type of high-altitude lightning. While there was no evidence that these jets were triggered by cloud-to-ground lightning, extremely low-frequency (ELF) radiowaves associated with four of the jets were detected in Antarctica and Japan, indicating negative cloud to ionosphere discharges. These observations are now making atmospheric scientists think in new ways about the still poorly understood planetary electrical circuit.

Further reading

H T Su et al. 2003 Nature 423 974.