I assume dry and moist air are different in density. Is that difference large enough to make a balloon float?
I mean moist air in terms of relative humidity, as is used when talking about weather.
That depends on the material and geometry of the balloon, but is it even worth trying?
I think a simple balloon made of rubber as used as toy for children may create pressure, which is probably not helpful.
Is it worth trying to make a balloon containing completely dry air float in completely wet air, or the opposite of it?