dark lightning

They’d found the source of the dark lightning.

After dark, lightning flashed, not so much from cloud to ground as within clouds, illuminating their inner shape and structure.

Three sea lions streaked like dark lightning bolts underwater, then leapt onto a pile of boulders or the edge of the pool.

These bursts produce very little visible light, inspiring Joseph Dwyer to dub them "dark lightning".

Dark lightning appears sometimes to compete with normal lightning as a way for thunderstorms to vent the electrical energy that gets pent up inside their roiling interiors, Dwyer says.