(WFRV) – You may have noticed an icy glaze on the trees and some surfaces outside the last few days. It’s called rime ice and has been the product of foggy and below freezing start to the New Year.
The feathery crystals have provided for fantastic images across Northeast Wisconsin:
How exactly does the process work?
Freezing fog is when fog develops below the freezing point (32 degrees Fahrenheit). Fog can often develop when there are calm winds and warm air aloft moves in over cooler surface air. In order for rime ice to form, freezing fog has to be prevalent in the area.
The supercooled water droplets remain a liquid within the fog even though the air temperature is below the freezing point. Once these water droplets freeze onto surfaces, a white deposit of feathery ice crystals is formed which is now rime ice.
Driving conditions can be dangerous during freezing fog events as moisture can freeze to roadways causing slick travel, especially on bridges and overpasses.
Rime ice is different than hoarfrost although they are similar in appearance.
Hoar frost tends to form on clear, cold nights, when the water vapor, or gas form of water, directly forms into ice without passing through the liquid phase.
Hoar frost formation is the exact same process as dew formation. The only difference is dew forms when the saturation point of the air mass is above freezing.
To submit any photos of rime ice, send them to us on social media: