24c WavesPreview

The rim is the sky's light through the day — day, both twilights and night — with the sea drawn inside it.

The sun is up, and the day's own rules apply.

The blue hour: the sun is down, the sky still carries colour, and lights start to matter.

The next step down: the horizon is still there, but the day is over.

The sun is well down and the sky's warmth is gone.

The ticks and numbers around the rim are local clock time: one full turn is one day.

The line where the clock shifts: the hour the zone changes inside the day.

Arcs at the top of the day are events from a connected calendar, hung where they fall.

The faint reference circles divide the middle so a value's height can be read by eye.

The faint ring is the day's cloud cover, drawn where the sky meets the sea.

The line inside it is the UV index on its own scale — nothing at the inside, twelve at the outside — in the WHO's bands, so it steps rather than slides. Below three its colour is the plate, so a safe day's line is drawn and not seen.

The curve is the water's height through the day, with high and low water marked where they fall.

The wave, the arrows and the labels are the swell: how tall, how long between crests, and where it is going.

The colour of the sea band is the water's temperature — the wetsuit question, not the air's.

The line near the middle is the air temperature: nothing at the inside of its lane, forty at the outside, and a day below zero mirrors back out rather than in — the colour says which side of zero it is, and the value is printed every three hours.

Each sock points downwind — north is up on the dial — and its bands of orange and white count three knots each, the way a real windsock does.