Lightning strikes in super slow motion
What appears to be an instant flash is actually a two-pronged approach. Phil Ritchie explains.
Lightning travels at around 350,000,000 kilometres per hour – almost a third of the speed of light – making it appear a single flash to a storm-watcher.
But what appears to be a simple line of light connecting clouds to the ground is actually a little more complex.
Most people know lightning descends from storm clouds, but fewer know about the second bolt that rises from the earth.
Ningyu Liu from the Florida Institute of Technology in the US recorded lightning bolts on a high-speed camera at 7,000 frames per second – a speed necessary to capture the near-instant pace of each bolt.
This cloud-to-ground lightning is entirely visible in the video. But how does it work?
The lightning in the video starts out like a branch, creating a series of channels coursing from a negatively charged pool of electrons and ions, stirred up by wind and collisions within its cloud of origin.
As the branches trickle down, they pause after each movement for a fraction of a second before continuing.
When the frontrunner of one of these branches is close enough to the ground, a positively charged bolt rises from the earth, creating an ionised conduit out of molecules in the air – like a wire.
This conduit pulses with immense energy, thanks to the flux in voltage between cloud and ground.
As it transitions back and forth the conduit forms what we call lightning.