FZFG

MikeOH58

Well-Known Member
So i'm looking at the forecast for tomorrow and I see there will be Freezing Fog...I've never encountered this before. I presume it is fog when temperatures are below freezing? If so, sounds nasty and I imagine there will be a ton of ice on everything outdoors.

How bad is it?
 
So i'm looking at the forecast for tomorrow and I see there will be Freezing Fog...I've never encountered this before. I presume it is fog when temperatures are below freezing? If so, sounds nasty and I imagine there will be a ton of ice on everything outdoors.

How bad is it?

Not bad at all. The amount of ice build up on things on the ground, as well as the airframe while in flight, is dependent on the moisture density, i.e. fog has very small liquid drops compared to rain. The real enemy is freezing rain, especially with larger droplets/heavy rain.
 
I've seen ice fog at around zero or so fahrenheit. Now, as for what it does, not much, when its that cold there can't be that much moisture in the air, so you can't really expect that much ice accumulation, the problem with ice fog is its dense, and makes your approaches down to mins or below and may prohibit you from being able to make it in.
 
We have been having FZFG in the morning every day for the last two weeks. Driving to the Airport yesterday I could see about 20 feet in front of my car. It is dense and hugs the ground.
 
Well considering clouds can create structural icing and fog is essentially a low cloud, it would make sense for fog to exist and cause icing.
 
I've seen ice fog at around zero or so fahrenheit. Now, as for what it does, not much, when its that cold there can't be that much moisture in the air, so you can't really expect that much ice accumulation, the problem with ice fog is its dense, and makes your approaches down to mins or below and may prohibit you from being able to make it in.

Ice fog is not the same as freezing fog (FZFG). Ice fog is composed of ice crystals, the fog is literally ice, and it generally only occurs with temperatures below 35 degrees F. You will not get ice on the airplane from ice fog. Freezing fog is the fog equivalent of freezing rain. It's liquid in the air, and freezes when it hits a surface. It's generally no big deal for airplanes certified for ice since the rate of accumulation is very low.
 
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