The timebar

The map’s bottom bar, TIMELINE, is a ruler over the forecast’s hours. The pointer is the instant the map is drawing; everything else on the bar exists to say where that instant sits against the now and against the alerts.

The ruler

Three tiers of ticks — hours, six hours and days — and the bar decides which fit its width: on a narrow screen the days and six-hour marks survive. Every label is in Santiago’s domain time zone, never the browser’s; the zone appears under the title as an offset, like UTC-4, because an abbreviation changes with summer time and an offset does not.

Past, present, forecast

The demo simulates real time: there is a now that advances minute by minute, and the forecast stretches ahead of it. On the ruler, the past is shaded with a hard edge at the now. The top bar’s chip — PAST, PRESENT, FORECAST — says which side the pointer falls on; present is exactly one step. How that now is built, and why it repeats every 24 hours, is in the forecast cycle.

Following the now

On entry the view follows the now: the pointer advances on its own. Any deliberate move — dragging, clicking the ruler, a step in Controls or with the arrow keys, a click on a Series curve — stops the following and leaves the view where it was put. The Go to the current time and follow it button returns it to the now and resumes; while following, the same button reads Following the current time — click to stop.

Alerts on the ruler

Behind the ruler, hours in which any receptor exceeds a level are tinted in that level’s colour — warning, alert, critical — with the worst level across all receptors winning at each instant. It is the fastest way to see when the forecast turns difficult, before opening the Alerts panel. The N key jumps straight to the next one.

The controls

The Controls panel, on the right rail, moves the pointer without touching the ruler: Play and Pause, Step back and Step forward, Back to start and Forward to end; and two camera framings, Zoom to domain extents and Reset view. Play walks the forecast step by step: the layer moves with the wind, markers change colour as they cross a level. Space plays and pauses, ← and → step.

One more button chooses the size of a step: 15 minutes, the forecast’s own resolution, or one hour. Hourly stepping is what the regulatory reading wants — an hourly standard is compared hour by hour — and the button is there for air-quality species, which are the ones a standard covers.

→ The forecast cycle · Panels · Dimensions