Being just a few weeks away from my 50th birthday, I am now of the age when I get up at 2am for no good reason. Mind you, I always enjoy the night and the experiences that hardly anybody else has because they are asleep.
As I looked towards the west, I saw a brief flash of light. It was lightning, obviously very far away, its light scattered by a cumulonimbus parent cloud.
Sprites: completing a global ground-ionosphere circuit.
After looking at the lightning strikes map, it turned out a cluster of strikes had just occurred in County Mayo, western Ireland - 325km away. That comfortably beat my previous sighting record of 280km from two years ago.
This sparked some conversation at home about lightning sprites. As usual, to keep the kids' attention in dad's crazy science, a quick YouTube video helps get the essentials across. At about 11m30s in to the video, I then realised that all this global current cycle, as mediated by sprites, should be something to keep in mind in terms of HF propagation. See if you have the same idea:
