flash of lightning; lightning bolt
Refers to the visible flash or bolt of lightning itself. Often used in literary or descriptive contexts.
A flash of lightning streaked across the night sky.
fire caused by lightning
Specifically a fire that starts when lightning strikes something. Less common than the first sense.
The mountain burned from a fire caused by lightning.
Hexagram 55: Abundance (Feng)
Compound of 雷 (rai, 'thunder, lightning') and 火 (ka, 'fire'). The exact historical derivation is uncertain, but the kanji straightforwardly represent the meanings.