Bill noticed:

... clothes will dry faster on less humid days than when it is raining.

That's true outdoors, especially when it is raining :-)

...if you were to vent the dryer into the house, the dryer intake air would
be very humid and the dryer would have a difficult time drying the clothes.

I don't think so.

... recirculating the moisture; out the dryer, then back in again.

The drying rate should be proportional to the difference between the vapor
pressure at 100% RH at the dryer temp, say 130 F with Ps = 4.53" Hg, and
the vapor pressure of house air, eg Pa = 0.299 for 70 F at 40% RH or 0.449
at 60% or 0.748 at 100%, which is much smaller, so the house RH should make
little difference in drying time. Clothes that dry in 20 minutes at 40% RH
with Ps-Pa = 4.23 might dry in 20x4.23/(4.53-0.449) = 21 minutes at 60%.

OTOH, they might dry in 20x4.23/(0.748-0.299) = 188 minutes (3.1 hours) in
70 F air at 40% RH and 20x4.23/(0.748-0.449) = 283 minutes (4.7 hours) in
70 F air at 60% RH, with the help of a fan. At 100%, they would never dry,
theoretically-speaking.

They might dry in 2 hours (120 minutes) in a house with 70 F air at 60% RH
if 120 = 20x4.23/(Ps-0.449), so Ps = 1.204 "Hg = e^(17.863-9621/(460+T)),
which makes T = 84 F, with a Holmes HFH111 1500W compact heater fan ($12.88
at Wal-Mart) set to 84 F in a closet, in series with a humidistat that turns
it off when the closet RH drops to 60%.

Nick