You can see the west (left) side attic vent near the peak.
There is another vent on the east side, above the #1 Sanyo outdoor unit.
There is also a ridge vent along the top of the peak.. A lot of the heat escapes there.
The attic intake (for the blower) is very near the center of the attic..
I have not paid any attention to the late night attic temp, I think it depends on how fast and far it drops..
Early in the AM, the attic has been about 1 degree warmer than the outdoors..
Must be leakage from the Sanyos and the difference in altitude of the sensors.
~~Edit~~~
Started the logger at 10:34 this morning. Came back and it was still working!
According to the math for a 200cfm air flow, in 30 minutes, you can move 6,000 cubic feet of air!
So, all the air in my basement is being changed twice an hour..
We discovered that holding onto the hardwood banister on the way downstairs,
we can easily 'feel' the temperature change, as you near the middle steps.
Up top, the banister feels warm, but as you decent to the point where
the angled overhead meets the basement ceiling, the wooden rail becomes quite cold, to the touch.
That's the point where the warm air slides into the basement, along the basement ceiling.