Pictures of rare Frost Flowers
Kentucky State Climatologist Emeritus
Frost flowers are an early gift of winter that fills the heart with a feeling like that of the first crocus of spring. But, these frost flowers are made of ice! They are an artistic display forged by the weather.
Frost flowers grow when conditions include unfrozen soil that is moist from a previous rain, clear skies that allow the temperature to drop to 28˚F or so for the first time in the fall, and weeds. The “frost weeds” like white wing stem are really good producers of frost flowers.
The process begins when the water inside the weed stem becomes super cooled. The water moves up the stem by capillary action. When the wall of the weed stem splits from the pressure within, super cooled water is extruded through the split and freezes upon contact with the air. Typically, the ice that forms is about the thickness of a credit card. The length of the split constrains that dimension but commonly exceeds six inches. As super cooled water continues to extrude and freeze, the formation is pushed farther outward from the stem often reaching three inches or more. The frost flower “blooms” when the ribbon of ice bends or curls to present flower like shapes, no two of which are identical. Frost flowers are fragile, shattering when touched, and they usually sublimate as the air temperature rises soon after sunrise.
The photographs were taken in Allen County, Kentucky. Photos 1=5 were taken 17 November 2007 and 6-10 on 6 December 2009.
 Verbesina vir0ginica L, also called white crown beard
 Super cooled water’s temperature is below freezing but remain liquid
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