A 24-hour clock whose face is painted with the computed colour of the sky at a chosen place, for every minute of the day. Noon is at the top and midnight at the bottom; the horizon is at the centre and the rim is high sky, looking toward the sun. Pick any place on a globe, drag the hour hand or the ring of days, and see sunrise, golden hour, the three twilights and night.
The colours come from a physical model of the atmosphere computed in the browser: Rayleigh scattering by air, Mie scattering by haze, ozone absorption and Earth's shadow, with the sun's real position.
By Karim Douieb, a klet.app experiment.