January 3, 2011, Crystal Mountain Gondola Cruise

Amar,

Don't talk too loudly or you might ruin this guy's day

He made two million vertical feet of back country runs in a single year (just completed his goal a few days ago).

www.greghill.ca/pages/the-2-mill-day/

Looks like he tracked it all on his watch.  Hopefully he had some kind of super accurate altimeter watch.

Just a guess but I'm pretty sure Amar was probably already aware of Greg Hill's 2 mill

Amar, I agree the only was to accurately total vertical is using the lift stats. I don't think, however, that dynamic pressure is increasing the Avocet's vertical reading. Full dynamic pressure would only be an issue if you wear the altimeter on your head with it's pressure port facing directly forward causing a Stagnation Point .
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So, depending on where you wear it, it could read higher, the same, or lower than actual altitude as you mode. Since I keep my Avocet in my fanny pack behind me in a low pressure area at speed, does it read less vertical than reality? Since I ski faster than my buddies , why do our altimeters read nearly the same at the end of the day?

I've always thought the Avocet's errors were more related to its temperature compensation and differences from body heat and/or sunlight messing with altitude.
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Thanks for a stimulating a romp through the fluid dynamics I haven't thought about for many, many  years.  Took some Wiki roaming to ramp up the memories.

I guess after years of observing that my Avocet usually gave fairly accurate top/bottom elevations (depending on weather), but always counted a few percent too much vertical (and never ever counted too little), I decided that dynamic pressure might be the reason. That effect can only add extra vert, never decrease your vert, because you still come to a stop at top and bottom, so any negative effect must vanish to zero. Other effects related to temperature compensation, inversion layers, etc., could give either positive or negative errors in counting vert -- yet my Avocet has never once undercounted vert in hundreds of days of use, all errors have been positive.

After years of occasionally thinking about it, I finally decided a few years ago to calculate the amount of error that dynamic pressure could cause. I expected the effect to be small and unimportant, including for the reasons you state, of the watch sensor not facing the wind directly. But when the numbers worked out so perfectly, giving 30-85 ft of error at typical fast skiing speeds of 30-50 mph, which just about matches the usual error per run, it seemed like a good match, and therefore the likely cause. If the watch is worn exposed on the wrist (as I do, usually barely covered by a glove cuff), it can certainly end up close to the stagnation point on one's knuckles. The only skiing speed that matters is the maximum speed on the last flat heading onto the lift, higher speeds at other points in the run have no effect at all, since you haven't yet completed the full descent for the dynamic pressure effect to add onto. So unless you are skiing significantly faster than your partners on the flats approaching the lift, your altimeters should read nearly the same.

If you like fluid dynamics (or statics), then one of the interesting things I discovered while doing the calculation is that the dynamic pressure effect, expressed in units of height (ft or m) is nearly independent of elevation, all the way up to 30,000 ft -- for example, 50 mph causes a 84.9 ft effect at sea level, while the same speed at 15,000 ft causes a 85.1 ft effect. The reason is that in the Standard Atmosphere, the rate of change of pressure with height (dP/dH) increases upon climbing higher just as fast as the density decreases, so the product of dP/dH and density is nearly constant from sea level to 30,000 ft. It's not quite exactly constant, but the product only varies from 1 to 1.005 (in arbitrary units) from 0 to 30,000 ft.

Anyway, I've never been fully certain that dynamic pressure is the reason for the always-positive Avocet errors, and I'm always open to other suggestions. I guess there's a very simple test to see if dynamic pressure is part of the cause: have the watch count ascent instead of descent, and see if the error is closer to zero, since the lift is moving a lot slower than I'm skiing. I've never tried this test yet, but I'll do it the next few times, and see if the typical error changes.

Amar,
Don't talk too loudly or you might ruin this guy's day
He made two million vertical feet of back country runs in a single year (just completed his goal a few days ago).
www.greghill.ca/pages/the-2-mill-day/
Looks like he tracked it all on his watch.  Hopefully he had some kind of super accurate altimeter watch.

I hope he didn't stop at 2,000,716 ft -- looks like he did though. If I were going for a mark like that (one where accurate counting is difficult and fraught with error) and then publicizing the result so heavily, I'd want to exceed it by a few percent at least -- say 50-100K extra in this case, just to be safe. But I'm happy for him that he reached his personal goals.

If he's counting vert while skinning up, then obviously dynamic pressure has no effect, he's moving far too slow (even Greg Hill!). But over a multi-hour ski ascent, real pressure and temperature changes will cause errors of a few percent on any watch (even with the best temperature compensation, you can't overcome real pressure changes), and those could end up either positive or negative. For a variety of complicated reasons, those errors tend to be positive more often than negative, but that depends on the weather conditions and atmospheric pressure profile during each of his ascents.

DDK-I'm not a real vert counter, but 65,000 is a pretty attainable number of vert if you are just yo-yoing the groom for 3/4 of a day. I'm sure you do it all the time and just don't realize it.

Joedabaker - I was wrong to question the vert totals for Amar and admit that I have heard of “big” vert numbers in the past and realize that some folks have those kind of days. My big (relatively) vert days have been when I was yo-yoing REX (as you say) because nothing else was remotely skiable (or it was a perfect slush cup day down the REX chair line in the Showtime arena). But I can pretty much swear on the good book that 65k days are not some accidental thing that has ever happened in my current life. Most days for me involve skiing bumps in the Valley, the front side of REX, runs down Powder Bowl into Bearpits, various lines up in Campbell Basin and even the hikes out south to the King (or the be nice to friends runs out North). Kinda like today, lots of folks were running the Gondy, but my best runs were in Bearpits and on Exterminator….cant make to much vert per minute on those runs…and also I’m kinda old and hardly ever make last chair ride. I have a Avocet and sadly am kinda of a vert counter.

I'll give Amar another kudo...just looked at his Club Vert statement again....14 days for the season and 819,000 vert....I just did my 30th day and only have 828,000....dang I'm slow and old.

I still count my vert but am more of a quality vs. quantity guy these days.

Joedabaker -  I was wrong to question the vert totals for Amar and admit that I have heard of “big” vert numbers in the past and realize that some folks have those kind of days.  My big (relatively) vert days have been when I was yo-yoing REX (as you say) because nothing else was remotely skiable (or it was a perfect slush cup day down the REX chair line in the Showtime arena).  But I can pretty much swear on the good book that 65k days are not some accidental thing that has ever happened in my current life.  Most days for me involve skiing bumps in the Valley, the front side of REX, runs down Powder Bowl into Bearpits, various lines up in Campbell Basin and even the hikes out south to the King (or the be nice to friends runs out North).  Kinda like today, lots of folks were running the Gondy, but my best runs were in Bearpits and on Exterminator….cant make to much vert per minute on those runs…and also I’m kinda old and hardly ever make last chair ride.  I have a Avocet and sadly am kinda of a vert counter.

I know that the numbers really rack up quick. When we skied the hope For the Cure a couple years ago I did not want to pull a vertical George, but just enjoy the day ski my thing. We went all over the place with several Right angles to the trail and even a King hike to end the day and we had 55,000 vert normal skiing. So it really racks up even doing bump runs and bear pits and the queen.

Hey, at least your out there skiing, whatever the totals. I'll take that any day over work!
Good on ya Amigo!