Definition
The rapid, continuous electrical discharges that travel down an already-ionized lightning channel, triggering the second and any subsequent return strokes in a multi-stroke lightning flash. Unlike the initial stepped leader, dart leaders move smoothly and quickly because they follow a path the first stroke has already cleared.
Plain English
After lightning strikes once, the air it traveled through is still hot and conductive. A dart leader is the fast electrical surge that shoots down that same path, causing the next flash. It's why a single bolt of lightning often appears to flicker — each flicker is another stroke fired down the channel by a dart leader.
Context Anchor
Seen in aviation weather study when learning how lightning forms inside and below thunderstorms.
Derivation
Called 'dart' because it moves like a thrown dart — straight, fast, and along a path already established. 'Leader' because it leads the way for the return stroke that follows it. The contrast is with the 'stepped leader' of the first stroke, which advances in jerky 50-yard segments.
Why Pilots Care
Recognizing dart leaders helps pilots understand lightning activity in storms and the risks of aircraft strikes.
Grounding Statement
When you see lightning flicker two or three times in what looks like one bolt, dart leaders are firing down the same channel to trigger each flicker.
Intuition Check
Dart leaders are not people or aircraft leading anything. They are fast electrical discharges moving along a lightning path that already exists.
Example Sentence 1
The flickering appearance of a lightning strike is caused by dart leaders triggering several return strokes down the same ionized channel.
Example Sentence 2
Lightning sensors on the aircraft registered the quick pulses typical of dart leaders.