return stroke

The term "return stroke" refers to a specific part of a cloud-to-ground lightning event. After a stepped leader, which is a channel of negative charge, descends from a thunderstorm, it induces a positive charge on the ground. When the stepped leader gets close to the ground, an upward discharge from the ground meets it. This junction creates a highly luminous and powerful surge of current, known as the return stroke, which is what we perceive as lightning.1

This return stroke travels rapidly upward, illuminating the lightning channel. Sometimes, subsequent return strokes can occur. These are initiated by a dart leader that travels down the existing lightning channel. When this dart leader effectively connects a charge center in the cloud to the ground, another return stroke follows. Multiple strokes can make lightning appear to flicker.2