Why will not the pitcher sweat in fine weather?
Because the air contains only a small quantity of moisture in fine weather.
Why does moisture sometimes collect on a glass window in a warm room?
Because the glass cools the air, and causes its moisture to collect in small drops on the glass.
What makes the glass cold enough to condense the vapor in the air?
The cold air, outside of the room, in contact with the glass.
Where does the moisture in the air of the warm room come from?
It comes from the breath of persons, and from the steam of the tea-kettle.
When the breath is blown on a cold object, like a piece of glass or metal, what is the result?
The moisture in the breath is condensed by the cold object, and is collected in small drops of water on its surface.