A race sky tied to its real location
A sky in Gran Turismo is more than a decorative backdrop. The game draws on historical meteorological data for the real-world location of a circuit, using it to shape atmospheric conditions such as cloud cover. That gives the sky a connection to the place and time represented in the simulation, rather than making every venue share the same generic weather look.
Why the stars can change, too
The sky is also tied to the track’s geography and the chosen time. Earth’s rotation changes which parts of the night sky are visible from a particular place, so the stars above a circuit can reflect its real-world position instead of being randomly scattered scenery.
This is a different kind of realism from modeling tire grip or suspension: it makes the setting feel situated in the real world. A familiar circuit can have a sky that belongs to its location, adding another small cue that the race is happening somewhere specific.
