[leaf345]

I was wondering if someone could help me with this question:

"It is raining outside and temperature is 2 degrees Celsius.  It is 20 degrees Celsius in your apartment. What is the relative humidity in your apartment if the central air system brings in air from the outside without changing the absolute humidity and heats it up to 20 degrees celsius?"

Because absolute humidity stats constant, I'm assuming that vapour pressure stats constant and the only thing that changes is the saturated vapour pressure. The problem is I don't know how to calculate the change in saturated vapour pressure. Does anyone have any advice?

[Borek]

http://en.wikipedia.org/wiki/Clausius-Clapeyron

or look for tables. Second approach is the one I would take.