Nothing stuck today, departing from +2C through to -7C. But I don’t think there was any snow once I was above the 0C level.
Quite scenic at ~4500ft:
What would be the mechanism for it to stick? Presumably if it’s still snow, either it’s dry or the ambient temperature is above zero. It can collect through geometry (impact icing in intakes and gaps etc.) but it shouldn’t “stick” to surfaces.Quote
At certain temperature combinations, I certainly have had snow stick to the leading edge, as ice would, but it does not seem to accumulate in the dangerous way that ice would. Snow accumulation seems to reach a point where it has reformed the airfoil at the stagnation point, and thereafter, it blows off. Once everything as a few degrees below freezing, this stops being a problem.
Flying through snow is not an issue as such. It can reduce visibility a lot if you arrive at the airport while it is snowing. Flying through snow at night can be cool. Turn on your headlight and you feel like you are flying through space :-)
It depends 
Last month I was flying through snow at night in Turkey with ice building up from time to time and getting rid of it with TKS in TB20 hand flying in full IMC – it wasn’t so cool. Two weeks ago I did the same in DA42 (after I was lost in fog on ground at LYBE) without ice build-ups and actualy it was fun.
@Peter, if you’re worried about the snow flake being part ice and part supercooled liquid, I agree with the others, I don’t think that happens. If the temperature is below zero and there is an ice nucleus present, the freezing should happen very quickly.
@bookworm, once a liquid cloud starts glaciating, the process is usually quick and complete (the main processes are water vapor diffusing from the supercooled liquid onto the ice particles due to the lower vapor pressure, and droplets colliding with ice particles and freezing). This is especially true if there is frozen precip falling through most of the cloud, because then the supercooled liquid is assured of seeing some ice go by. The exception is the cloud top, which is usually the last to glaciate because it will see the least sedimenting ice, so that could still be liquid in a snowing cloud. It’s possible that the probability of finding a liquid top is correlated with snow intensity through some kind of cloud dynamics, but I’m not aware of any research. I would be interested in hearing people’s personal experiences, too.
Since winter is just around the corner, @bookworm ‘s question is probably foremost on everybody’s mind. Therefore (and because I made the plot anyway for a vaguely related paper) let me try to give a less useless answer than my previous one…
I’d be more interested to know if anyone has had icing in a cloud from which dry snow is falling, or whether such a cloud is sufficiently glaciated that there’s no supercooled liquid water.
Here is the fraction of snowing clouds (dry snow) with liquid tops. The precipitation detection is from a spaceborne cloud radar (CloudSat); the phase at the top of the precipitating layer is from a spaceborne lidar (CALIPSO) that sees (almost) the same clouds as the radar. So snow is no insurance against supercooled liquid.
Does this mean that supercooled water droplets can exist in the same 3D position as snow?
In purely vertical terms this must be possible, because e.g. freezing rain can be made by snow falling through a warmer layer, etc.
I’ve had snow stick to the blades of my r/c helicopter so it must be possible. It made a rough layer a few mm thick, and as I recall the snowflakes falling at the time were fairly large and soft. The main hazard was finger numbness due to the cold, so I landed and went home.
Does this mean that supercooled water droplets can exist in the same 3D position as snow?
The data set I plotted doesn’t tell us, because the lidar will not penetrate very deep into the cloud. It will only catch the “typical” mixed-phase cloud case, where the bulk of the cloud is glaciated but the top is still supercooled liquid.
I would think that supercooled cloud droplets in the same 3D position as snow would get collected by the snow very quickly. With the caveats that
1) I wouldn’t bet my life on it…
2) then there’s your scenario of
In purely vertical terms this must be possible, because e.g. freezing rain can be made by snow falling through a warmer layer, etc.
which will give you a mixture of partly molten snow flakes (which should refreeze quickly, since they contain an ice nucleus) and freezing rain (from the smaller snow flakes, which have melted completely). The freezing rain drops fall fast enough that they won’t get collected.
But that scenario will look like freezing rain the moment you enter it. I was addressing @bookworm ’s scenario,
I’d be more interested to know if anyone has had icing in a cloud from which dry snow is falling, or whether such a cloud is sufficiently glaciated that there’s no supercooled liquid water.
i.e., entering a dry snow cloud and suddenly encountering supercooled liquid. And from my plot, it looks like there is a good chance that can happen, if you climb into the supercooled liquid top.
Sow is many different things. The Sami language have 200+ words for snow. I have flown in light snow showers several times (VFR), the main problem in 99.9 % of the cases is visibility. Heavy snow is impossible VFR in any case, but no problem for IFR except you need remove the snow and de-ice before take-off. Adverse temperature gradients and snow could be problematic I guess?
Digging up this old thread, there seems to be a consensus that snow will not stick to the aircraft.
What about temperatures above 0C. Often one gets perfectly normal looking snow and the temperature reads say +2C. Would that not stick? It ought to melt eventually but it may take time because the snow itself must be below 0C otherwise it would not be frozen (at least not at low altitudes).
