Our breaths condense.

December 27. 

Grows cold in the evening, so that our breaths condense and freeze on the windows.

H. D. Thoreau, Journal, December 27, 1859

See January 30, 1854 ("The windows are all closed up with frost, as if they were ground glass.");December 28, 1859 ("In the morning the windows are like ground glass (covered with frost), and we cannot see out."); January 4, 1856 ("It is snapping cold this night (10 P. M.). I see the frost on the windows sparkle as I go through the passageway with a light ")'; February 1, 1860 ("Frost forms on windows."); February 5, 1855 ("It was quite cold last evening, and I saw the scuttle window reflecting the lamp from a myriad brilliant points when I went up to bed."); February 6, 1855 ("Frostwork keeps its place on the window within three feet of the stove all day in my chamber."); February 17, 1860 ("Grows colder yet at evening, and frost forms on the windows.")