One Of Winter’s Most fascinating wonders

Rime ice forms when either freezing fog or a cloud of supercooled water droplets makes contact with a surface below freezing. For reference, freezing fog forms when the air becomes fully saturated with water vapor below freezing, causing water to condensate into super-cooled drops.

When the supercooled water droplets make contact with a given cold surface, they freeze on contact, leading to ice accretion. The air trapped by rime ice gives it a granular texture. This distinguishes rime ice from regular ice as it is formed from supercooled water droplets below freezing, not normal liquid water cooling to its freezing point.

If the fog or cloud is being blown, or you are flying in an aircraft through it, rime ice will form in the direction of the wind. For example, rime ice can build up on the front side of planes, such as the wings or propellers, adding weight and slowing the plane down. This is a key reason why planes are de-iced in between landing and taking off.

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Rime ice can also form on antennas when facing the wind and even on your clothing if you are exhaling into a cold enough airmass, such as while running.

Hayden Marshall is a meteorologist intern and First-Year-Master’s Student at the Georgia Institute of Technology. He has been following weather content over the past three years as a Storm Spotter and weather enthusiast. He can be found on Instagram and Linkedin.