おはようございます when it's not morning?


In a comment to [this answer](https://japanese.stackexchange.com/a/6729/1628)
it was mentioned that おはようございます can be used in a variety of situations other
than in the morning.

To me it only makes sense to say "good morning" when it is actually morning in
some sense. Are there truly situations in which おはようございます is appropriate, but
"good morning" would not be?




おはようございます is often used as a start greeting in work situations, whatever time
it may be, as opposed to the end greeting おつかれさまです.

I know it's used in the TV and entertainment industry (it was the question of
a quizz), and I've heard teachers use it to welcome their pupils as late as
19:30.




おはよう or おはようございます is used when the time is considered as the beginning of a
day in some sense. For example, if the addressee has just waken up, it is
appropriate to use おはよう(ございます) even if it is not in the morning. On the other
hand, if you stayed very late at workplace until 1 o’clock in the morning and
met a colleague who was likely to have done the same thing as you, you would
not say おはようございます, because it is considered to be the continuation of the day
before rather than the very early period of a day.

