Freezing fog explained: How the right conditions create this supercool weather
Outside of Alaska, freezing fog generally only occurs in mountain regions. But here it's just a part of day to day life — especially in recent days.
Along with the recent cold snap, freezing fog has engulfed much of the state as temperatures fell below zero. Although similar, freezing fog, fog and ice fog or frozen fog are all different forms of fog.
Simply put, fog is just tiny little water droplets suspended in the air. Water vapor condenses under the right atmospheric conditions basically forming a cloud that rests on the ground.
In fog, those tiny drops of water are just that — water. But when the air temperature falls below 32 degrees, something interesting starts to happen.
The tiny water droplets fall below freezing as well, but they don’t freeze.
The water suspended in the air is so pure that it can actually dip below 32 degrees and remain water. We call this supercooled water and that is what freezing fog is — a bunch of really tiny supercooled water droplets.
When the temperature drops low enough, those tiny water droplets freeze. When the water suspended in the air is actually frozen, that is ice fog or frozen fog. It's something rather common in the Interior when the temperature drops well below zero.
In the case of freezing fog, those supercooled water droplets remain liquid until they encounter something that causes them to freeze. This can be the branch of a tree, the ground, or even dust in the air.
Upon contact with the foreign object, the liquid water instantly freezes. We call this rime ice.
Rime ice looks just like hoar frost and coats trees all the same. The biggest difference is the formation — rime ice forms from the fog where hoar frost forms in clear conditions.
In Alaska, the low sun angle and short days make for some wild winter weather. But no matter how cold it gets, the state is a truly beautiful place.
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