Roger Shoaf wrote:

"Duane Bozarth" wrote in message
...
Roger Shoaf wrote:
...
At 70% humidity dew will not form on the ground, so it should not form
in
your attic.

Not necessarily so...dew may well form on the ground just not in the air
as fog and may OP may well condense moisture out in the attic on cold
surfaces even if the bulk air temperature is above ambient.

At 70% humidity the only way to get the water to come out of the air is to
lower the tempriture of the air to the dew point. If the air is in motion,
it will not be incontact with the colder surface long enough to cool and
therefore condense.
....

Just not so...if air movement is fast enough, yes, you may avoid
it...but it's not necessarily so, and it is possible for there to be
cold surfaces that are below the ambient air...

There's not enough data for to tell whether that is or is not the case
in OP's case, but it is certainly a possiblilty to look for...