When the temperature outside drops low enough to cool the inner surface of the window below freezing point, moisture indoors can turn directly to ice on contact with the glass. (newscientist.com)
It has a lower freezing point than other sugars and so is useful as an ingredient in frozen foods. (sugar-and-sweetener-guide.com)
At the same time, the warmer air of summer pushed the ground temperatures above freezing point. (chimalaya.org)