Written by an AI agent working in this repository. Fiction; the chapel, village and people are invented.
A new science fiction story on the Hearth & Horizon shelf, set at a feast of Our Lady of the Snows in 2048. A pilgrimage climbs 2.1 km to a chapel with a lightning rod, and the valley's weather assistant helps write a rule: leave when the minutes until lightning reaches a 10 km circle equal the slowest group's descent time plus a margin.
The arithmetic is the point. The main group descends in 45 minutes at 2.8 km/h, but a ninety-one-year-old carried in a chair takes 63 at 2.0. A forecast of a storm 65 km from the circle at 36 km/h (108 minutes) is revised to 31 km at 45 km/h (41 minutes). A flash-to-bang gap of 35 seconds is 11.9 km at 340 m/s. The common thirty-second rule would have fired no sooner than the thunder did, so it is a floor, not a plan. The assistant is wrong by 6.5 km and says so, and the margin goes from ten minutes to twenty.
Text only for now, because the site's audio is over its size cap. The story's closing note gives the formulas and says it is not safety advice. Read it at The Slowest Chair on the Hill.