Jan 21, 2013 at 8:00 am #1298267
spelt with a tBPL Member
@speltLocale: SW/C PA
I'm wondering if you choose insulation differently for a windchill of 0F vs an actual temp of 0F with no wind, and also if humidity is a factor in your decision. Theoretically, moving air would rob more heat than still air, and low humidity would increase evaporative cooling while high humidity would inhibit same, but practically I don't have experience with a wide enough range of conditions to know how much, if any difference this makes.Jan 21, 2013 at 1:25 pm #1945852
@b-g-2-2Locale: Silicon Valley
If you are in a zero wind situation, then having a wind shell on is OK, but it isn't necessary. Once you are in a high wind situation, then the wind shell is really worth its weight in gold.
I think of a wind shell as keeping the cold out and keeping the warmth in. Those are just two sides of the same coin.
–B.G.–Jan 21, 2013 at 4:11 pm #1945901
Rick MBPL Member
delJan 21, 2013 at 4:25 pm #1945906
Erik BasilBPL Member
I do. My upper body system includes a rain shell as the outer layer and I only really vary the inner, insulative layers for temperature. This results in a system that always accommodates wind chill.
However, my lower body system does not. Mostly, this is because manfacturers tend to make stuff for shrimpy little people…uh, persons of minimal inseam :) and they don't fit me in products I can buy. So, I use thicker capilene for my legs, under larger cut hiking pants, but I definitely change what I'm bringing based on both ambient temperatures and predicted wind/precip.Jan 21, 2013 at 11:50 pm #1946047
Well if the air temperature is 30F and the wind is 25mph the wind chill would be 0F. I would wear a something to block the wind over the a insulated layer. For no wind at 0F I would have to wear more insulation to compensate for the air temperature difference.Jan 22, 2013 at 12:37 am #1946052
@rcaffinLocale: Wollemi & Kosciusko NPs, Europe
> Also pretty sure at 0F the RH is nill.
Nope. Water vapour pressure still exists at 0 F, even if it is rather low.
CheersJan 22, 2013 at 3:06 am #1946059
David ThomasBPL Member
@davidinkenaiLocale: North Woods. Far North.
Yes, I would choose clothing differently for an actual temp of 0F (with no wind) and a wind chill of 0F.
At 0F, no wind, I'd have more insulation but less continuous wind-blocking layers.
At 0F wind chill (20F blowing 20 mph?), I'd have a bit less insulation but good a good wind shell top and bottom. Also, I'd have a better sealing hood and probably a neoprene face mask. Whereas with no wind, a simpler hood without a face mask would suffice.
Consider, however, that a wind can come up. Where I am, there is a large marine influence, so if it is -20F, there can't be any wind. And if it was -20F and the wind came up, the temps would rise markedly. But in inland locations, you can get wind without a temperature increase and you need to be ready to respond to that.
Under a good wind shell, you are somewhat immune to the wind-chill effects. Not completely, but mostly. But as wind increases, gaps at the cuffs, waist, collar and any bare skin of the head/neck needs to be addressed.
Humidity definitely effects me in the tropics – and I factor it in to clothing and what level of exertion I can manage. Read up on "heat index" (the reverse of wind chill) for info on that.
But in winter, at home in the Arctic, no, I don't factor in humidity. The absolute humidity is low if the temps are low, so any air that gets into my clothing will have low RH when warmed by my body. That actually makes clothing choices easier because non-wonder-fabrics (cotton, wool, silk) dry out if you are perspiring. Much better, though, is to adjust clothing BEFORE you sweat so you don't soak the clothes in the first place. The more I remember the Inupiat concept of "never sweat", the better any clothing works at sub-freezing temperatures. Another traditional approach I come to appreciate is tunnel hoods and a fur ruff. It creates a region of still area in front of your face that I prefer to googles and face masks fogging up and getting coating with snotsicles.Jan 22, 2013 at 7:59 am #1946081
Jerry AdamsBPL Member
@retiredjerryLocale: Oregon and Washington
You have wind penetrating your clothing that you can prevent with a wind proof jacket and tight junctions between materials.
Also, there's the boundary layer that David mentioned in another post. In still air there's significant insulation value. If it's windy it get's blown away so you need a little more insulation inside.
Isn't this what wind chill is all about? Not about air penetrating clothing. Because they talk about how it feels on your skin.
Maybe this applies more to sleeping when you're more likely to have still air.Jan 23, 2013 at 7:23 pm #1946616
Tjaard BreeuwerBPL Member
@tjaardLocale: Minnesota, USA
Yes, in general I don't look at the windchill very much for these cold temperatures.
I choose the amount of insulation based on the absolute temperature, and the amount of wind protection based on the wind speed.
So, in 20F, 20mph wind I might wear light insulation with a thorough wind layer all over, including some kind of face protection and tight seals at cuffs etc.
By contrast, at 0F I would wear significantly more insulation, but no, or much less of a windshell. this has the benefit of reducing condensation.
However, for convenience sake, since wind speed changes frequently, I usually wear a shell even when there is little wind, and just adjust my insulation and venting/face covering.
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