The Electrical Light Show in the Sky
Lightning strikes are electrical discharges on a massive scale between the atmosphere and an earth-bound object. They mostly originate in thunderclouds and terminate on the ground, called Cloud to Ground (CG) lightning. However, they may also be initiated from a very tall grounded object and reach into the clouds.
Although "a lightning strike" is commonly used to describe all lightning, it is rather erroneous and a misnomer, as only about 25% of all lightning events worldwide are CG. The large bulk of lightning events are Intracloud (IC) or Cloud to Cloud (CC), where discharge only occurs high in the atmosphere.
The scientific name for the complete process of a single lightning event is a “flash”, and a flash is a very complex, multiple step interaction, which is not entirely understood. Most CG flashes only “strike” one physical location, referred to as a termination. The primary conducting channel, the bright coursing light you may see and call a “strike”, is only about one inch in diameter, although to our eyes it looks much larger. They are miles long, and can be upwards of tens miles long. The entire flash lasts only fractions of a second, and most of it is not visible to the human eye.