: Kinetic energy in the local environment dropped below measurable levels.

He didn't feel the cold anymore. He only felt the stillness. The Mechanics of the Stillness

Elias was in the high Sierras when the shift reached the ground. He was a man who lived in the margins of the world, a seasonal ranger accustomed to the biting teeth of a mountain winter. But this was different. The wind didn’t just stop; it seemed to solidify. The pine needles, usually flexible even under a coat of frost, became brittle as glass. When a bird tried to take flight from a nearby branch, it didn’t fall; it simply hung there for a heartbeat, its wings locked in mid-stroke, before shattering into a thousand sapphire shards upon hitting the permafrost.

A different (e.g., a futuristic city, an underwater base)