https://j0̷.lolgood morning is a Spherical Wedge of the earth that rotates at the pace of one day per full rotation
im not entirely sure if you could determine how wide the wedge is. like is there a determined hard cutoff for when morning ends and afternoon begins or does this become something culture-specific. could we all agree on a start time and end time for morning as a collective human population
all i know is that if you are in the wedge you can say good morning and if you arent in the wedge it would not be proper to say good morning
i think the night to morning boundary is more interesting actually. because people do wake up at like 4am to go to their jobs are they having a good morning? (probably not...)
it would definitely be improper to say good morning at midnight but i could see 4am or maybe even 3am
if you factor into this that timezones are discrete and not continuous the wedge would just teleport every (half, quarter) hour. also timezones are not always contiguous from pole to pole so theres a chance it would be two broken wedges. or worse