Distant artillery fire can resemble a natural phenomenon like lightning

Evidence

It was a quick, isolated flash, with nothing of the soft palpitation of heat lightning; instead it was as if a heavy hammer behind the horizon were pounding out red-hot iron on an enormous anvil with regular strokes. — Julien Gracq, Balcony in the Forest, 388

Categorization

• corroborated: 2 independent passages support this claim — Julien Gracq, Balcony in the Forest, 388