The naimittika or occasional pralaya is the dissolution with a schedule: it arrives at the end of every kalpa, when Brahma's day closes. The Puranic descriptions are set pieces of apocalyptic grandeur. A drought of a hundred years empties the world; the sun's rays multiply and become seven suns that drink the remaining moisture and set the three worlds burning; Vishnu as Rudra consumes creation in fire, then as a vast cloud floods the ash with rain for another hundred years until a single ocean covers everything. Upon that ocean the creator sleeps, and the texts linger on the image: Vishnu reclining on the serpent Shesha, whose name means remainder, that which is left when the world is subtracted.
Through the night of Brahma the dissolved cosmos persists as potential, and at dawn creation is not invented but remembered, unfolded again along the same lines. Two features distinguish this from the apocalypses of the Abrahamic traditions. There is no judgment: dissolution falls on the righteous and the wicked alike, because it is not a verdict but a phase. And there is no finality: the night is exactly as long as the day, and the next day is certain. The doctrine's emotional register is correspondingly different, not terror before an ending but something closer to the calm of tides, immense, impersonal and reliable.