FAA: class D if tower closed
Hello,
one of the simple questions again turns out to be really difficult:
What precisely happens to a D or C airspace if the tower is closed?
The AFD says "other times CLASS G", for some C it even says "other time CLASS G, CLASS E 700 AGL and above".
While the latter is pretty clear, the D bothers me. What is the ceiling of G replacing D at night? Is it 700AGL or 1200AGL or the ceiling of D during the day (which is 2500AGL).
Where is this quite important information written down? I couldn't find anything in the FARs or AIM.
Also, what happens to an attached class E surface area? It would be weird if the E sfc area remains effective while the D "core" itself becomes G.