natural event vs periodic event

Other hyponyms of natural event include accompaniment, attendant, co-occurrence, concomitant, avalanche, experience, trouble, treat, miracle, marvel, wonder, thing, episode, contingence, contingency, eventuality, beginning, conclusion, ending, finish, one-off, recurrent event, alteration, change, modification, computer error, error, accident, chance event, fortuity, stroke, fire, incident, discharge, case, example, instance, motion, movement, failure, success, appearance, destiny, fate, disappearance, disappearance, contact, impinging, striking, finish, collapse, break, interruption, sound, union, news event, flash, convergence, juncture, occasion, burst, flare-up, outburst, eruption, irruption, outbreak, black eye, blow, reversal, reverse, setback, bonanza, boom, bunce, godsend, gold rush, gravy, manna from heaven, windfall, collapse, crash, supervention.