“I love hoarfrost. I think it’s one of the most beautiful things in the world,” said Aurora Clark, associate chemistry professor at Washington State University. Frost and snow crystals are influenced by the underlying hexagonal structure of water. Frost crystals form on a surface, which dictates what types of patterns emerge. Snow crystals, which form in clouds, grow more freely. Temperature and humidity also affect the shape of frost and snow crystals.
Fern frost forms on a car window at Hauser Lake on Tuesday, Nov. 26, 2013. Window frost (also called fern frost or ice flowers) forms when a glass pane is exposed to very cold air on the outside and moderately moist air on the inside.