A vocabulary of landscape — a landscape of words
1068 entries
window frost
Window frost is the branching feathery ice pattern that grows on the inside of a cold window when moist indoor air meets glass below freezing. Water vapor turns straight to ice on the surface without becoming liquid first, and the crystals grow outward from scratches, dust, and imperfections in the glass, which is why the pattern is different on every pane.
Etymology
The English term is plain, and the folk name is Jack Frost, the figure held to draw the patterns overnight, whose origins have been traced variously to Norse tradition and to eighteenth-century English personification with no clear answer. The pattern is also called fern frost, ice flowers, and frost flowers, the last of which names two other things on this site.
Notes
It is much rarer than it used to be, which is a straightforward consequence of double glazing: An inner pane that stays close to room temperature never gets cold enough. Anyone over a certain age in a cold country grew up with it and anyone younger has largely not seen it, which makes it one of the few natural phenomena that a building technology quietly removed from ordinary life.