In the US, there are some airports with a part-time tower. When the tower is in operation, the airspace around the airport is class D and requires communication with the tower. When the tower is closed, the airspace would be either class E or G (depending on height AGL) and pilots would land at the airport like they would an untowered airport. (Right?)
Assuming that is true, what happens to traffic already in the area when airspace becomes class D with communication requirements? Are the pilots supposed to "evacuate" the airspace before when it becomes class D? Or are they "adopted" by the tower when it opens?
If they are "adopted" what is that process and communication like?
If there is already a "busy" class E & G pattern (maybe with 3 airplanes in the pattern and one having just touched down) in process, what would we be likely to hear from the tower as they open? (Are there any separation requirements that class D airspace control would be trying to meet that a "busy" class E/G traffic pattern would not meet?)