A day here takes a real twenty four hours. The world clock runs on real UTC at real speed.
You see the sky above your own longitude and latitude. Two players on opposite sides of the world are in daylight and darkness at the same moment, correctly. Your night is as long as the real night where you are standing. At 51 N in December, that is about sixteen real hours of darkness.
What follows from that
- Mobs follow your sun, not a server clock.
- Daylight sensors read night everywhere. There is no single server time for them to read.
- Snow and sea ice advance and retreat with the calendar.
- Animals appear in the months and the latitudes they really live in. Polar bears are not there all year.
- Villagers wear the clothes that match the real ground they are standing on.
- Rain puts out fire that is under open sky. Lightning still starts fires.
- Very large forests do not rot away on their own. Leaves only decay near a tree you cut down yourself, and that tree still decays normally.