Who is Jack Frost?

Jack Frost is an elf from Scandinavian legend that was named Jokul Frosti, meaning Icicle Frost by the Norse Vikings. The son of the Nordic wind god Kari, he became Jack Frost after his story arrived in England. He is renowned for his artistic talents of painting beautiful frost designs on windows and plants late at night.

Other cultures have their own folklore. Japanese legends name Frostman and brother Mistman as keepers of the frost and dew. In Finland Frostman and Frostwoman control the weather and must be placated with sacrifices. Then Russian legends identify frost as Father Frost, a blacksmith who binds the earth with his chains of ice. While German folklore tells of Old Mother Frost who shakes feathers from her bed that become frost as they float to earth.

Scientifically, frost can be defined as the ice crystals that form when water vapor adheres to freezing surfaces. The fancy frost that decorates our windows is called fern frost and forms when a glass pane is exposed to very cold air on the outside and moderately moist air on the inside. Water vapor condenses on the glass and as it freezes ice crystals grow forming feathery, lacy, patterns on our windows.

Hoar frost or white frost is the white ice crystals that loosely cover everything outside when temperatures dip below freezing and there is an ample source of water vapor.

Another less common form of frost is called rime frost. Rime frost appears as needles or spikes. It can develop more quickly than hoar frost, especially during windy conditions when liquid water droplets come into contact with freezing surfaces. Rime frost is the white extensions that you see on the crab apples pictured. It doesn't have a crystalline structure, and is more matte and less sparkling than hoar frost.