Too Cold For Ice

spiderweb

spiderweb

Final Approach
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Ben
What types of clouds are absolutely too cold for ice accumulation?

Flying today, there were puffy CU at 5,000 where the temperature was about -15C.
 
spiderweb said:
What types of clouds are absolutely too cold for ice accumulation?

Flying today, there were puffy CU at 5,000 where the temperature was about -15C.
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0ºK

-15C still has icing potential.
 
We only need to use the anti-ice in visible moisture down to -35C so I think that would be a pretty safe number. Of course you probably don't see it too often at altitudes smaller airplanes operate.
 
Well I had to go to -35 to get the ice to stop on this trip....it was NE N and then NW of the noreaster....
 

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spiderweb said:
What types of clouds are absolutely too cold for ice accumulation?

Flying today, there were puffy CU at 5,000 where the temperature was about -15C.
Click to expand...
I don't know about types of clouds, but the theoretical lower limit for supercooled liquid water to exist is -40, and without supercooled liquid water, you won't get structural icing.

Do you know the short workshop on Scott D.'s site called Too Cold For Ice? There's a lot of good info in there, and it's only about 10 minutes long.
 
azure said:
I don't know about types of clouds, but the theoretical lower limit for supercooled liquid water to exist is -40, and without supercooled liquid water, you won't get structural icing.
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Is that -40F or -40C ?

<running and ducking>
 
Steve Foley said:
Is that -40F or -40C ?

<running and ducking>
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:rofl:

In any event, the probability of icing starts to drop off below -10C (about +10F), and gets extremely low below -20C (about -10F), but the possibility still exists at least in theory down to -40C (which, as those with a calculator can determine, is the same as -40F).
 
I'm trying to think the coldest I've ever gotten ice. Probably about -25C. That said, since pitot heat and prop heat don't cause me any performance loss, I just leave them on from about +5C on down.

Of course, it's not that often I'm flying in -40C/F weather, but I have.
 
Everskyward said:
We only need to use the anti-ice in visible moisture down to -35C so I think that would be a pretty safe number. Of course you probably don't see it too often at altitudes smaller airplanes operate.
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Wow..
 
So, that day, with friendly-looking scattered CU would have been fine, but flying through one of those clouds--friendly though they may be--may have given me ice, I understand. It wouldn't have been long, as they weren't even 1,000 feet thick, and I could easily deviate (unless ATC wouldn't let me). But the SR20s I rent have no de-ice except pitot heat and a defroster.
 
It really all depends on cloud type. I was recently on a flight in a Cessna where we had an altostratus layer at 5000' with -8C in the clouds and +2C above them, didn't even get a frosting. I could clearly see glaciated particles bouncing off the wings at some thick points though. But if we had gone through a nice set of nimbostratus clouds (which are quite rare in winter in the NE unless there is associated precipitation like snow) it could have been different solely because the potential for icing in those clouds are more prevalent because in most cases they are much more saturated then any other stratus type.
 
thezoolityre said:
It really all depends on cloud type. I was recently on a flight in a Cessna where we had an altostratus layer at 5000' with -8C in the clouds and +2C above them, didn't even get a frosting. I could clearly see glaciated particles bouncing off the wings at some thick points though. But if we had gone through a nice set of nimbostratus clouds (which are quite rare in winter in the NE unless there is associated precipitation like snow) it could have been different solely because the potential for icing in those clouds are more prevalent because in most cases they are much more saturated then any other stratus type.
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I am just reluctant to try poking through those -15c clouds I describe in an SR20, because the wing does NOT like ice, and since the surface was well below 0, I would be landing an iced wing.

I will admit, the only time I ever experience ice anything more than frosting was in a de-ice Twin Commander. I was amazed at how fast it built up.
 
spiderweb said:
I am just reluctant to try poking through those -15c clouds I describe in an SR20, because the wing does NOT like ice, and since the surface was well below 0, I would be landing an iced wing.
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Me too, Ben. And I was sorely tempted on Sunday because it was so bumpy, and the layer was so thin.. But I knew they were stratocumulus clouds, which can have a lot of liquid water in the tops even at -15C. My destination was clear but that could have changed in a few minutes and I'm not sure how long it would have taken to sublimate whatever I picked up anyway. Subfreezing surface temps take away an important option.
 
azure said:
Me too, Ben. And I was sorely tempted on Sunday because it was so bumpy, and the layer was so thin.. But I knew they were stratocumulus clouds, which can have a lot of liquid water in the tops even at -15C. My destination was clear but that could have changed in a few minutes and I'm not sure how long it would have taken to sublimate whatever I picked up anyway. Subfreezing surface temps take away an important option.
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In non-deiced aircraft, they sure do.
 
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