Absent the Sun (and the Moon), what do the terms "morning" and "evening" mean? Remember those were not created until IIRC the third day.
Even after the Sun and Moon were created, to what geographical region did the terms "morning", "evening", and "day" apply? Remember that, except during a solar eclipse, it's always "day" somewhere on the planet and "night" somewhere else.
The bible doesn't seem to deal with the whole world as we now know it to be. The flood seems to have been regional also.