Red sprite and the global electrical circuit
This photo comes with the explanation:
Explanation: There is something very unusual in this picture of the Earth — can you find it? A fleeting phenomenon once thought to be only a legend has been newly caught if you know just where to look. The above image was taken from the orbiting International Space Station (ISS) in late April and shows familiar ISS solar panels on the far left and part of a robotic arm to the far right. The rarely imaged phenomenon is known as a red sprite and it can be seen, albeit faintly, just over the bright area on the image right. This bright area and the red sprite are different types of lightning, with the white flash the more typical type. Although sprites have been reported anecdotally for as long as 300 years, they were first caught on film in 1989 — by accident. Much remains unknown about sprites including how they occur, their effect on the atmospheric global electric circuit, and if they are somehow related to other upper atmospheric lightning phenomena such as blue jets or terrestrial gamma flashes.
Never havinbg heard of the global electrical circuit, I followed a link to discover:
Lightning is not an event isolated within the confines of a thunderstorm. It is part of a massive electrical circuit that literally covers the globe. The voltage difference between ground and ionosphere is 200,000 to 500,000 volts (200 to 500 kV). Even in fair weather, a slight current of 2 pA (picoamps, or 0.0000000000001 A) flows from every square meter of ground upward to the ionosphere. Thunderstorms alone send 1 A of current skyward. Indeed, the flash rate for a storm is directly related to its current flow.
While this view is widely accepted, it has not been proven by hard data. The [Lightning Imaging Sensor] LIS, and a Lightning Mapping Sensor, would clear up many of the uncertainties about the global electrical circuit. Lightning images would enhance data from ground-based lightning networks by catching the cloud-to-cloud flashes that ground networks miss.