“Lightning travels from the ground up”

It's a common sight to see lightning seemingly strike down from a turbulent sky, leading many to believe that these powerful electrical discharges always travel from the clouds to the ground. This visual interpretation is a significant reason why the idea of lightning originating high above and descending has become so widely accepted, an intuitive conclusion given the storm's lofty perch.

Scientifically, the dramatic flash we observe actually moves in the opposite direction. The process begins with an invisible, negatively charged "stepped leader" descending incrementally from the thundercloud. As this leader nears the ground, it coaxes positively charged "streamers" to rise from objects below, like trees or buildings. When a stepped leader and a streamer finally meet, they create a conductive channel.

The moment this connection is made, a massive and incredibly bright electrical current, called the "return stroke," surges rapidly up this channel, from the ground towards the cloud. This upward surge is the intensely luminous event we perceive as lightning. Because this return stroke travels at an astonishing fraction of the speed of light, our eyes register it as an almost instantaneous flash, masking the initial, slower downward movement of the invisible stepped leader and giving the illusion of a top-down strike.