Need a "snow distance" factor

[Cookerhiker]

I recently returned from a week of schlepping through snow on the AT in SW Virginia. I hiked 61 miles but it felt like 100! As I walked through an average base of 8 inches of virgin snow and waded through thigh-high drifts in some places, I’ve decided that we need a “snow distance” factor similar to the “wind chill factor.” If the latter tells us that 20 degree temperatures with X level gusts of wind translated into 0 degrees, why can’t the scientific nerds develop something that for example says that hiking 12 miles with average depth of 8 inches and 1/4 mile of drifts averaging 2 feet translates into hiking 16 miles? Of course, you also consider snow density (wet & heavy vs. dry powder) and perhaps the size of the person since snow depth is absolute not relative. What do you think?

[Youngblood]

I recently returned from a week of schlepping through snow on the AT in SW Virginia. I hiked 61 miles but it felt like 100! As I walked through an average base of 8 inches of virgin snow and waded through thigh-high drifts in some places, I’ve decided that we need a “snow distance” factor similar to the “wind chill factor.” If the latter tells us that 20 degree temperatures with X level gusts of wind translated into 0 degrees, why can’t the scientific nerds develop something that for example says that hiking 12 miles with average depth of 8 inches and 1/4 mile of drifts averaging 2 feet translates into hiking 16 miles? Of course, you also consider snow density (wet & heavy vs. dry powder) and perhaps the size of the person since snow depth is absolute not relative. What do you think?

I think you just qualified as a charter member of the WhiteBlaze.net Scientific Nerd Society.

[Frosty]

I recently returned from a week of schlepping through snow on the AT in SW Virginia. I hiked 61 miles but it felt like 100! As I walked through an average base of 8 inches of virgin snow and waded through thigh-high drifts in some places, I’ve decided that we need a “snow distance” factor similar to the “wind chill factor.” If the latter tells us that 20 degree temperatures with X level gusts of wind translated into 0 degrees, why can’t the scientific nerds develop something that for example says that hiking 12 miles with average depth of 8 inches and 1/4 mile of drifts averaging 2 feet translates into hiking 16 miles? Of course, you also consider snow density (wet & heavy vs. dry powder) and perhaps the size of the person since snow depth is absolute not relative. What do you think?

I hate to admit ownership in Youngblood's Scientific Nerd Society, but here is what I think:

The hiking is snow factor is a peceived factor. It is not directly measurable. Even if you could make assumptions for all the variables, the resultant calculated "effort" would not be equal for every one (ie, not a predictor of effort). It is similar to the "one pound on the feet is equal to five pounds in the pack rule." It is not a rule, of course, and cannot be proven mathematically. It is just someone's idea whose legs get tired in haeavy boots.

Wind chill, on the other hand, is a precise calculation that is clearly defined.

Here is the formula used:

T(wc) = 0.0817(3.71V**0.5 + 5.81 -0.25V)(T - 91.4) + 91.4

T(wc) is the wind chill, V is in the wind speed in statute miles per hour and T is the temperature in degrees Fahrenheit

The only problem with wind chill is that it doesn't directly apply to people or human skin. There is a correlation, to be sure, but it is similar to the "pound on the foot or in the pack" rule in that you have to accept the underlying assumptions that the above formula does indeed match the effect of wind on exposed skin. My personal experience is that wind chill is HIGHLY over-rated, the actual temperature has much more effect on exposed skin in cold temperatures than wind. On the other hand, in milder temps (50-60 degrees) wind is a big factor IF the skin is damp, due to evaporative cooling effect.

Wind chill is supposed to give you an idea of how quickly flesh will lose heat (and thereby freeze). Important factors that are ignored in the wind chill index are the circulatory capabilities in the individual invovled (good circulation will re-warm the area and nullicy the effects of the wind), part of the body affected (legs unaffected by wind chill at all, at least as far as freezing goes, but ears in particular are vulernable than wind chill would indicate), and such umdane things as individual differences in how quickly one person loses heat through the skin as opposed to a different person (factors might include amount of body hair, thickness and resilience of epidermal layer, etc.)

On the other hand, it is pretty cool to tell friends, "Yeah, I backpacked one night in the Whites and the wind chill was minus 65." Sounds better than, "It was 20 below and windy."

My two cents.

[Frosty]

Unable to edit earlier post. Please note:

I meant "nullify" not "nullicy"

"ears in particular are vulernable than wind chill would indicate"
should be
"ears in particular are more vulernable than wind chill would indicate"

"umdane" should be "mundane"

[Lugnut]

I think you would make a good playmate for Weather Carrot. He's really into that kind of stuff.

[Joel Rash]

"Every mile is two in winter."

George Herbert
English clergyman & metaphysical poet (1593 - 1633)

[Youngblood]

Frosty,

I'll send you directions for the Society's secret handshake once I verify that our email link is secure.

Youngblood

[Blue Jay]

"Every mile is two in winter."

George Herbert
English clergyman & metaphysical poet (1593 - 1633)

This is about right for me any way, hard to say for others. I run a few trail races each year and also a few snowshoe races. My times for the snowshoe races are between 1.75 and 1.85 of my trail races. Plus I think the colder temperatures suck the extra energy out of you to make up the difference.

[Brushy Sage]

Just curious as to what kind of clothing you were wearing -- apparently protected you well enough while trudging through the deep snow! Thanks.

[smokymtnsteve]

what brand/type snowshoe do you use Blue Jay?

[chris]

If I'm in snowshoes, it means I'm carrying a lot of winter crap anyways and wearing big boots, so the 2-1 notion is about right. With 8 inches of snow, I wouldn't be in snow shoes, wouldn't be carrying a lot of winter crap, and the ratio would be back at 1-1.

[Cookerhiker]

Just curious as to what kind of clothing you were wearing -- apparently protected you well enough while trudging through the deep snow! Thanks.

Brushy Sage since I started this thread, you were directing this question to me? I generally wore 3 layers on top - polypro shirt, fleece pullover, waterproof/breathable shell (made in Ireland; works real well). Bottom, I wore spandex with waterproof rainpants plus gaiters. I had non-waterproof Vasque hiking boots. Also wore rag wool hat and gloves. The deepest snow (thigh-high drifts on Walker and Gullion Mts in SW VA March 2) was light and powdery so I stayed dry. Later on with slushier and wetter snow, my feet did get wet. At night, I added fleece pants and rag wool sweater. Rread about it at:
http://www.trailjournals.com/cookerhiker2005

[Blue Jay]

what brand/type snowshoe do you use Blue Jay?

They're Solomons, I like them but they are noisy. I use Atlas for Backpacking.

[smokymtnsteve]

I have a set of redfeather...

I like the bindings on the atlas...but are they good for breaking deep powder?

[Frosty]

If you have a well packed trail (no postholing) and no severe dropoffs, you can make great time on downhills in the snow by sitting on your butt. I've come down major portions of the Fishing Jimmy Trail and Crawford Path that way. It helps if there are no people climbing at the time. For some reason, many people object to seeing a 250# man careening wildly down the trail straight at them at 20 mph with this snowshoes sticking up in the air aimed at them. Go figure.

[Blue Jay]

I have a set of redfeather...

I like the bindings on the atlas...but are they good for breaking deep powder?

No better than redfeather

[The Solemates]

"Every mile is two in winter."

George Herbert
English clergyman & metaphysical poet (1593 - 1633)

So the 20-mile days we were doing in the Smokies with over a foot of snow....we were actually doing 40-mile days?

I dont think so....

[The Old Fhart]

Frosty-“ Wind chill, on the other hand, is a precise calculation that is clearly defined. Here is the formula used:”

The formula you list was correct until 11/01/2001 when they changed it. When I was working on the summit of Mt. Washington for the Observatory the winter of 2001-2002, the buzz was about the wind chill temperature index formula being changed after decades. Click here to see the new formula and the science behind it. Wind Chill (°F) = 35.74 + 0.6215T – 35.75(V**0.16) + 0.4275T(V**0.16). The new formula should take care of some of the shortcomings of the old.

Specifically, the new WCT index:
* Calculates wind speed at an average height of five feet (typical height of an adult human face)
* Is based on a human face model
* Incorporates modern heat transfer theory (heat loss from the body to its surroundings, during cold and breezy/windy days)
* Lowers the calm wind threshold to 3 mph
* Uses a consistent standard for skin tissue resistance
* Assumes no impact from the sun (i.e., clear night sky).

They do have an online calculator for wind chill but the interesting thing is that that doesn’t work for the extremes I saw on the summit of 145mph winds at -34°F. Although we normally think of wind chill at temps below freezing, wind chill in the 40°F-50°F air temp range makes hypothermia a real summer time danger in the mountains. Most deaths in the whites are in the summer from “exposure” and being damp from sweat or sitting on damp ground can increase the heat flow away from your body up to 25 times faster.

[weary]

I always thought the "old" windchill was a bit of a fraud. The new formula is better. But I don't pay much attention to either. With decent insulation and a wind break outer layer, my problem while actually hiking is staying cool, not getting too cold.

Windchill is a perceived thing. I doubt if many ears or noses have been frosted with a below zero wind chill -- providing the Farenheit temperature remains above 32. And I'm positive no water in a bottle has ever frozen unless the F is below the freezing mark.

Having said this, I'm sort of glad there was no wind the New Years that the temperature dropped to minus 32 and the Baxter Park Rangers forgot to unpadlock the Katahdin Stream bunk house for us.

Weary