Subject: Why do doors slam when there is a window open?

I've noticed for years that the door slams when someone closes it at normal 
pressure, if there is a window open in the room, even with no apparent wind 
and the blinds are closed.

I'm asking out of curiosity. I've wondered about this for a while, and can't 
find the answer by googling it.

It seems the answer must have something to do with air flow, but the door 
slams so hard it seems like a huge wind must be pushing against it. But there 
is no wind at all.

Re: Why do doors slam when there is a window open?