The barometer’s needle has walked downhill like a person who forgot lunch. Pressure falling. The thermometer and the little hygrometer agree: the air is wet enough and cold enough that water cannot stay invisible. Fog is a cloud on the ground. Here it is advection fog, Tess said—warm moist air sliding over a cold sea, condensing into a million tiny mirrors.

Those mirrors eat headlights. They make lamps look nearer. They make you feel followed.

You write: T near dew point. Pressure dropping. Fog = weather math, not a mood.

The cottage table has room for a true night if you lay the papers out. The horn shed would like those numbers beside a delay-count, so the moan has a weather report instead of a eulogy.

Fog is not smoke and not magic and not a mood, though it can borrow all three costumes. Each droplet is a tiny lens. A million tiny lenses make a wall that is not a wall. You breathe them. They cool your face. They make the lantern a wet moon. You check that your socks are still dry, because cold plus wet is a math problem you are not here to fail. The hygrometer’s hair or coil or whatever cheap guts it has is doing its small job: air is full. Air is ready to bloom into weather.