Boulder "Harder" than 5,000ft at Equator According to Torres in Today's Chasing Glory: Wrong?

Personally I find it more difficult to run fast in Boulder than in Kunming or Lijiang (6200ft and 7400ft, respectively). I dont know why this is.

It's hard to run with rocks in your head, I'm guessing.

Elevation isn't the key....air pressure and density are the big ones. Not sure about Boulder, but they often say that 20K feet on Denali is equivalent to 23 or 24K in the Himalayas. Closer to the equator generally has higher pressure for a given elevation above sea level.

This

gravity wrote:

Since it is decreased gravitational force at altitude that decreases partial pressure on oxygen molecules which in turn makes it more difficult for our body's to assimilate oxygen (not a decrease in the count of oxygen molecules), it is distance from the center of the earth, not from sea level, that causes the effects athletes seek when training at altitude."

contradicts

"An often-cited result of Earth's equatorial bulge is that the highest point on Earth, measured from the center outwards, is the peak of Mount Chimborazo in Ecuador, rather than Mount Everest. But since the ocean, like the earth and the atmosphere, bulges, Chimborazo is not as high above sea level as Everest is.

the earth's atmosphere bulges as well so there is a negligible difference between the mass of atmosphere above 5000ft. at the equator vs. 5000 ft elsewhere. the mass is the same and the difference in g is miniscule. i would estimate that to find the answer you would need to do some extensive math, but that you would come up with very little difference indeed.

I'm no geologist, physiologist or atmospheric researcher, but I've heard statements from the like which would diffute what the OP is stating.

I've heard that climbing Everest is only possible because of its (relative) close proximity to the equator. If Everest sat at the same latitude as Denali, than it would be nearly impossible to climb - as if it wasn't already.

As a Boulder resident, I've heard countless times from our high altitude friends from Mexico, Ecuador, etc., that it is much more difficult to train in Boulder than their respective (and higher) homeland. I remember Barrios claiming that he could do 1K repeats quicker in Mexico City than he could do at the CU track.

Perhaps the humidity plays a factor in this, as Boulder's relative humidity is very low in general. I remember when Machuka? broke 28 minutes at the Bolder Boulder. It was so foggy that day that you could barely see the athletes.

train town wrote:

I remember Barrios claiming that he could do 1K repeats quicker in Mexico City than he could do at the CU track.

Perhaps the humidity plays a factor in this, as Boulder's relative humidity is very low in general. I remember when Machuka? broke 28 minutes at the Bolder Boulder. It was so foggy that day that you could barely see the athletes.

What would his weight difference be, between Mexico City and Boulder?

I would think fog would make breathing more difficult, and low humidity make breathing much easier.

back off man, i'm a scientist

your answer is here:

http://mtp.jpl.nasa.gov/notes/altitude/AviationAltiudeScales.html

there is lots of truth to what the op has to say.

Your moment of science:

The layer of air that covers our planet is insubstantial compared to the mass of the planet. The troposphere, which contains 80% of the atmospheric mass, only extends to 5 to 11 miles above the surface of the planet. This would correspond to no more than the thickness of a heavy layer of paint for a 10 inch classroom globe. The thickness of the troposphere is not uniform over the earth. A combination of centrifugal force and temperature differences make the troposphere thickest at the equator, 10 to 11 miles. It is only 5 to 6 miles thick at the poles. Due to lower temperatures the troposphere is more dense at the poles, and the net result of all contributing forces and factors is that air pressure is pretty much the same planet wide at sea level. At high altitudes this is not true.

Since the air layer over the earth is thinner at the poles, any upward movement from the planet's surface passes through a greater portion of the air layer than the same movement would accomplish at the equator. Thus, for higher altitudes, air pressure at high latitudes is lower than it is at low latitudes.

We can not quantify this effect until we address seasonality. In the winter the air mass over the poles cools and contracts, and the thickness of the planet's local atmospheric layer decreases. (Of course, the opposite pole is experiencing summer and its air layer is expanding.) Thus, in winter at high latitudes and high altitudes air pressure is further depressed.

Now, to quantify: consider the altitude at which air pressure averages 0. 5 atmospheres. On Mt. McKinley, 63: N latitude, this altitude is, on the average, 18,400 feet in mid-summer, and 16,800 feet in mid-winter. In the vicinity of Mt. Everest, 30: N latitude, this altitude is 19,400 feet in mid-summer, and 18,850 feet in mid- winter.

At the summit of McKinley, 20,320 feet actual altitude, the average air pressure in mid-summer is about 0.453 atmospheres, which would correspond to a Himalayan summer altitude of 21,650 feet. In winter the summit pressure for McKinley, 0.420 atm., corresponds to a Himalayan winter altitude of 22,800 feet, and a Himalayan summer altitude of 23,460 feet.

Chimborazo, 20,700 feet actual altitude, is essentially on the equator ( 2: S latitude) and so its summit pressure of about 0.472 atm. does not vary much seasonally.

my previous post will be lost on 99% of lr.c - which i cannot help. the secrets of science ... we keep them hidden in a book.

Found my answer:

Torres is correct and he isn't even a "geologist". While gravity is less at the equator, barometric pressure is higher:

Us Dept. of Defense:

"The mean barometric pressure at sea level is 760 mmHg(1013millibars) and falls as altitude increases. As theweight of upper atmospheric gases compresses the lowergas, this fall is not linear, the rate of decline in pressuredecreasing as the altitude increases. At the Equator, thebarometric pressure at high altitudes is higher thanelsewhere on the globe,11a phenomenon related to theparadox of the coldest atmospheric air lying above theEquator. Everest is at latitude 28oN, where the summitpressure is considerably greater than at a hypotheticalmountain of the same altitude near one of the poles.12The increase in barometric pressure of 17 mmHgbrought about by this so-called equatorial bulge isenough to improve maximal oxygen uptake and thusmake possible the ascent of Mt Everest without supplementary oxygen"

http://64.233.169.104/search?q=cache:45efbeI1syEJ:www.defence.gov.au/dpe/dhs/infocentre/publications/journals/noids/ADFHealthNov99/ADFHealthNov99_1_1_18-23.pdf+equatorial+bulge+oxygen+uptake&hl=en&ct=clnk&cd=1&gl=us

Wikipedia: Gravity

"Gravity is weaker at lower latitudes (nearer the equator), for two reasons. The first is that in a rotating non-inertial or accelerated reference frame, as is the case on the surface of the Earth, there appears a 'fictitious' centrifugal force acting in a direction perpendicular to the axis of rotation. The gravitational force on a body is partially offset by this centrifugal force, reducing its weight. This effect is smallest at the poles, where the gravitational force and the centrifugal force are orthogonal, and largest at the equator. This effect on its own would result in a range of values of g from 9.789 m·s−2 at the equator to 9.832 m·s−2 at the poles.[1]

The second reason is that the Earth's equatorial bulge (itself also caused by centrifugal force), causes objects at the equator to be farther from the planet's centre than objects at the poles. Because the force due to gravitational attraction between two bodies (the Earth and the object being weighed) varies inversely with the square of the distance between them, objects at the equator experience a weaker gravitational pull than objects at the poles.

In combination, the equatorial bulge and the effects of centrifugal force mean that sea-level gravitational acceleration increases from about 9.780 m/s² at the equator to about 9.832 m/s² at the poles, so an object will weigh about 0.5% more at the poles than at the equator.[2]

Altitude

Gravity decreases with altitude, since greater altitude means greater distance from the Earth's centre. All other things being equal, an increase in altitude from sea level to the top of Mount Everest (8,850 metres) causes a weight decrease of about 0.28%. (An additional factor affecting apparent weight is the decrease in air density at altitude, which lessens an object's buoyancy.[3]) It is a common misconception that astronauts in orbit are weightless because they have flown high enough to "escape" the Earth's gravity. In fact, at an altitude of 400 kilometres (250 miles), equivilant to a typical orbit of the Space Shuttle, gravity is still nearly 90% as strong as at the Earth's surface, and weightlessness actually occurs because orbiting objects are in free-fall.

If the Earth was of perfectly uniform composition then, during a descent to the centre of the Earth, gravity would decrease linearly with distance, reaching zero at the centre. In reality, the gravitational field peaks within the Earth at the core-mantle boundary where it has a value of 10.7 m/s², because of the marked increase in density at that boundary."

Are you suggesting Jason is only a blockhead on US soil?

Man, scooped again! Well done, uhh dude.

For those of you having trouble visualizing why the atmosphere thins at the poles and bulges at the equator, imagine someone tossing pizza dough. Even though they start with a roughly sperical lump, by spinning it they quickly flatten the thing out. The reason planets aren't as flat as pizzas is their gravity is strong enough to hold everything in.

gravity wrote:

Mr. Torres let us know today on Chasingglory.com that a) 5,000ft above sea level in Boulder is much harder than 5,000ft above seal level at the equator and b) he's not a geologist and Mr. Carney agreed that he's not a geologist either. Regardless, awesome run finishing up Lefthand canyon!

Other way around, silly.

I also tip my hat to uhh, dude; I hope that more than 1% can understand that explanation, but those focusing on gravity seem to miss the primary effect at altitude.Also note that ski at high elevation in Europe leads to thin air due to latitude, altitude, and time of year - makes for faster bobsled rides.

cassio598 wrote:

Man, scooped again! Well done, uhh dude.

For those of you having trouble visualizing why the atmosphere thins at the poles and bulges at the equator, imagine someone tossing pizza dough. Even though they start with a roughly sperical lump, by spinning it they quickly flatten the thing out. The reason planets aren't as flat as pizzas is their gravity is strong enough to hold everything in.

Last year in Kenya, Canova told me the phenomenon regarding altitude at equator vs. at northern/southern latitudes, was was due to the scarce vegetation at colder locations such as Boulder vs. warmer conditions at Equater. - Also said that, probably, he was to write a book for IAAF about altitude.

The earth is not a perfect sphere.

This scientist guy should go back to 5th grade and learn that there is no such thing as "centrifugal" force, only "centripetal" in physics[quote]uhhh dude wrote:

"the troposphere is not uniform over the earth. A combination of centrifugal force and temperature differences make the troposphere thickest at the equator,"

uhhh dude wrote:

back off man, i'm a scientist

your answer is here:

http://mtp.jpl.nasa.gov/notes/altitude/AviationAltiudeScales.html

*there is lots of truth to what the op has to say*.

Your moment of science:

The layer of air that covers our planet is insubstantial compared to the mass of the planet. The troposphere, which contains 80% of the atmospheric mass....

Of course, the science you posted in indicates that Boulder is HARDER than the same elevation ASL at the equator. Opposite to what the original poster argued.

It seems to me you simply compare the typical or average barometric pressure in two locations to see if there is an effect. All the gravity and bulge talk is nice, but what IS the actual pressure?

That would indeed work if there were not rising air(pressure lows) and descending air (pressure highs) messing up the picture. But agreed on your broader point, that the mixture of gases in the air isn't changing, just the pressure.