Joseph Meehan wrote:

wrote:

...you might somehow drill a hole in the material at the edge between
the two panes and vent that to the outdoors. Warm air rises and humid
air rises, so that hole should eventually move the water vapor outdoors,
assuming it's less humid outdoors and the new exit hole is larger than
the tiny leak entrance holes.

...the humidity inside vs outside is not the proper measure.

Absolute is, relative isn't, but we also need to account for bouyancy.

I don't know about "bouyancy"...

Warm air rises and humid air rises... T = 70 F dry air weighs 0.075 lb/ft^3,
and this decreases with temperature as (460+70)/(460+T.) The density also
decreases with increasing moisture content, since the molecular weight of
water vapor is about 18 vs 29 for air... 70 F air at saturation (w = 0.0158)
weighs 0.073 lb/ft^3. A closed cavity with a hole near the top is a natural
"cold trap" as well as a "dry trap." (By contrast, igloos are heat traps.)

In wintertime, any warm or moist air that leaks into a glass cavity from
inside a house is likely to find its way out the top of the cavity via
a larger hole by bouyancy as well as diffusion. In summertime, with AC
in a house and cavity air cooler than outdoor air, warmer outdoor air is
lighter than cavity air, so it's unlikely to enter a hole at the top of
the cavity. Outdoor air with more absolute humidity is also lighter than
cavity air, so it's unlikely to enter a hole at the top of the cavity.

...they don't fog up as long as they remain sealed and they do fog up
when they loose their seal I don't think we are likely to find that
increasing the leaks as a good solution to the problem caused by leaks
to start with.

Drilling more holes in the TOP of a leaky boat might help a little :-)

Nick