To add to what Michael posted.
A few quotes from "Constructive Beekeeping" by Ed Clark
"A similar misunderstanding is on at the present time about
the best way to get rid of the moisture in the hive. The bees,
from the habits and customs, carried down for ages, contending
that condensation is the system best adapted to their mode of
life, while the beekeeper is trying to force them to use the ventilating
system. I think that the beekeeper, being a most sensible
person, will see the error of his way and eventually follow where
the bee leads. The bees but show their contempt for ventilation
when it is at its best."
"How do the bees dispose of the great amount of water carried
into the hive in the nectar? You say: “they evaporate it and it is
carried off by the air.” . But is it? Try drying the family wash in
a room of dimensions, as regards water to be evaporated, temperature
and opening at the floor, proportionate to the beehive,
and see how fast your wash dries. Be sure you have no windows
in the room to condense the water vapor. Try it when temperature
outside is 60 deg. F and the atmosphere one-half saturated,
(one-half saturated in the evening is about as dry as we find the
air in May and June where there is ample rain fall). Then try
it when the atmosphere is 9/10 saturated, and after this experience
you will be more amazed than: ever at the bees’ efficiency.
Still you are skeptical and remember that you should have
put an electric fan at the opening, because the bees are seen to
fan at the entrance. Let us not delude ourselves about the bees
moving all the water vapor, given off in ripening honey, out of
the hive by fanning.
Records of temperature and humidity taken from the U.S.
Weather Station at Moorhead, Minnesota, for three days at 7 P.
M. are as follows:
1916 Temperature Humidity
May 13 45.5 93
May 14 42.5 100
May 15 37.5 96
To remove from the hive one grain of water vapor by fanning
on May 13, the volume of air that would have to be moved would
be five or six times the air capacity of the hive. To remove one
pound of water would require the removal of a volume of air
equal to the capacity of from 30,000 to 40,000 hive-bodies. On
May 14 the outside air being saturated, no water vapor could be
removed by a change of air, and on May 15 the result would be
about the same.
From this it can readily be seen that little evaporation from
the nectar could take place by ventilation, and we are led to
believe that on such days as these the urge takes hold, giving
swarms the last week of May.
No contention will be raised when the statement is made that
the water is evaporated from the honey before we have ripened
honey. It has been taken for granted that as soon as the water
passes off by evaporation the bees were done with it. They
would be if this evaporation took place the same as from the
family wash hung on a line in open air. But if instead of having
the great volume of moving outside air, we have in a standard
hive body a little less than one cubic foot of air, where is all this
water vapor going to go? Saturate this small volume of air at
hive temperature and the water vapor in it would be from 1/600
to 1/5000 of what the bees evaporate in a night during a good
honey flow. If they saturated this air in the hive and then forced
it out at the entrance, they would cause rain in the hive near