400 ppm is an arbitrary benchmark, relevant to primates with ten fingers. It’s still important; it’s the atmosphere we must breathe.
From plots like this, it’s clear that the carbon dioxide content of our atmosphere is rising. It is probable that the rising temperature of the globe, the loss of Arctic ice, and the melting of our precious glaciers is related to human activity. I’m a cautious scientist; I’d like to see this experiment played out with many Earths and many rises of civilization to be sure. If forced, I’d have to bet on the prevailing scientific view that human emissions are driving global warming.
That’s not what this post is about. The rise of ~100 ppm over the span of the plot above has an alternate interpretation. 100 ppm is 0.01% of the atmosphere. That’s not a lot. But, our atmosphere is only one fifth (20.946%) oxygen, so it’s an effect that’s at least five times larger. Our oxygen is being burned into stuff we cannot breathe. Continue reading →
I’ve been toying with the idea of carbon poles for a while. With a gift card generously donated by Evo to the NSAS raffle burning a hole in my desk drawer, I finally gave in.
My original preference would’ve been the BD poles, on reputation alone, but they weren’t in stock for the season. A friend uses the Dynafit poles with gusto, adding a plus to the Dynafit column. This thread, however, makes me more than a little concerned for durability.
On to the real thing. With the usual concerns about extracting uncertainties from two measurements, the poles themselves weigh 180.9±2.4 g. The baskets are 13.5±0.4 g. In combination, they’re 194.4±2.4 grams. Dynafit’s claimed weight is 190 grams.
The Dynafit pole lowers aren’t round, they’re D-shaped, with notches cut in them to physically block the pole from slipping. The engineering and build quality feels very fine; time will tell if the complicated linkage will hold up to years of use. I’m rather partial to the BD flicklock system (why did BD move to something with more moving parts?!), but this system seems reasonable. Dynafit has a two-year warranty on the poles.
A thread over on Wildsnow got me digging back into the Off Piste data set. While in the past, I’d looked at weight per unit length vs girth, it’s also possible to plot against surface area (or surface density).
The ski surface area is computed with a formula which is both atrocious and practical. If M is a ski’s mass, S is the width of the ski shovel, W is the waist, T is the tail, and L is the length of a ski, then the density D plotted on the horizontal axis is
Be certain that you’ve used the right units (grams and centimeters, even for the width dimensions).
This treats the ski as two trapezoids, joined at the waist. This will tend to over-estimate the area of a ski, and hence underestimate its density. Relative comparisons of skis should be more accurate than the absolute density determined by this method. With densities determined this way, it would appear that anything in the 0.7-0.8 g/cm^2 realm is light by modern standards.
The Dynafit Cho Oyu’s claimed weight/dimensions would put it at 0.60 in these units (note that the pintail will pull the “trapezoidal density” down. Prototype skis from Ski Lab would land in the 0.64 realm.
I have a pair of OR Stormtrackers from 2010/11 that I really love – they’re my favorite glove ever. The softshell material keeps hands warm, but not too warm, in most temperatures we encounter in the Cascades. The Windstopper keeps things dry, at least until the DWR wears out. The old pair is now worn out/holey after two hard years of use, so it’s time for something new. What better to replace Stormtrackers than Stormtrackers? Found a minor winter/spring sale and bought a pair.
This year’s pair is red, which is nifty. The fit at the wrist isn’t as close as before, but the zipper closure does a better job of sealing at the wrist. Not sure which I’ll prefer. Dexterity is comparable. After some break-in, it may be equivalent.
What about weight? With the usual caveats regarding assessing uncertainty from two measurements, I measure 63.1±1.5 grams per glove, for size XL, or 126.1 g for the pair. The packaging claims 168 g/pair in size L, but the current OR website claims 116 g/pair for size L.
Vertfest is fast approaching, and plot-planning precedes performance, or something like that. Vertfest is an annual ski-mountaineering race held at Alpental and other venues. Alpental is closest to home, and most consistent. The race is split into roughly two divisions: a recreational route that goes to the top of the mountain and back down, and a race route that makes a second lap up and down a nearby knoll. Am I fast enough to avoid the cut on the race route? Don’t know – experiment is the arbiter of truth.
But first, an overview:
Age is largely irrelevant. Gender doesn’t matter much either. Savvy skills are the way to go fast.
A friend with a taste for lightweight skis brought these by for mounting. Apparently they’re a rarity here in the US. Before getting to the measurements, let me extend a hearty congratulations to Elan. Look at this excerpt from the Elan page:
There’s an errorbar on their mass! Alas, they don’t have masses for each size, but a huzzah nonetheless!
These skis are 1162 and 1145 g. So, the pair weighed (with the usual calibration and 2-point concerns) in at 1153±15 grams. This is easily consistent with their stated uncertainty. Thank you, Elan!
As this is a very light ski, I measured the widths as well.