Tuesday, August 4, 2009

Hiking and Climbing and Science: Day 1.

Last weekend while hiking with Carissa and Lin, I realized that the great outdoors is actually a great place to learn about science. This blog posting is going to be a combined report of our little weekend adventure, and some fun science along the way.

Conundrum Creek Trail:
The 8.5 mile hike from the trailhead is not a particularly hard one, even with full packs. It rises only a few thousand feet, and the trail is a smooth and beautiful walk. At the end of the hike, at 11,200 feet above sea level, is a campsite with some delightful hot springs which are almost famous according to this article. (No, that is not us in the photo).

The fact that such geothermal hot springs exist at all simply amazes me, but indeed they do exist, and are not even so uncommon in this part of the country where the ground was once volcanically active. In short, the water flows deep enough underground to get near a geothermal hot spot, and it comes up plenty warm. Sometimes it even comes up steaming as a geyser, or simply as water too hot to enjoy sitting in. The conundrum creek hot springs are particularly nice because they don’t smell like sulfur and they are just about bath temperature. After our hike, we had a nice soak.

Biophysics at Altitude 1:As you go to higher altitude the air pressure drops. At 11,200 feet, the pressure is only about 2/3 what it is at sea level. It is kind of surprising that the human body can adapt to such changes so readily. (However at only another few thousand more feet higher, extremely serious altitude sickness becomes common). A frequent word of advice when you travel to altitude is to drink a lot of fluids. This is not just because it tends to be dry up at altitude, but rather has something to do with helping your body develop a new chemical balance with the lower ambient oxygen levels. I scanned the web for a more detailed description of exactly why fluids help you adjust to altitude, but I did not find any good answers. If any biologists or MDs want to leave a comment I’d be much appreciative.

Since I only arrived at altitude in Aspen a few days earlier, I should have been a bit more careful about getting enough fluids. I had some pretty nasty leg cramps that evening (in places I have never had them before) and I think I can place the blame squarely on the altitude and my not taking enough water.

Biophysics at altitude 2: Maybe mosquitoes in Colorado are just plain stupid, or maybe they are genetically different from other mosquitoes – but in short, these critters are about as fast as Slowpoke Rodriguez, the slowest mouse in all of Mexico (i.e., very slow – and I apologize for the politically incorrect reference to one of my favorite bizarre loony tune characters). On the east coast (where people even talk quickly) you have to really have fast reactions to successfully swat a skeeter. However, out in Colorado up at 11,200 feet, swatting skeeters is like racing a running snail. Maybe this is because the air is so thin that they can’t get enough “traction” with their wings to fly away quickly. Or maybe they are just lethargic from lack of oxygen in their blood. Any entymologists want to ring in on this one?

Added: I asked around, and most people seem to think that the average mosquito is this slow and it is the east coast variety that is Speedy Gonzales.

As air rises and expands, it gets colder. A rough rule of thumb is that air drops about 5.5 degrees Farenheit per 1000 feet (roughly 1 degree Celcius drop per 100 meters). If you want a nice physics explanation of this phenomenon, see this page. At any rate, since Aspen is at 8000 feet, and at night it gets to be about 50 degrees, I should have expected it to reach about freezing up at 11,200 feet – and indeed, this was just about the temperature at night. Brrrr…

Since it was quickly getting cold out once the sun started to set, we had a quick dinner then jumped into our tents and into sleeping bags to keep warm. Unfortunately, at about 11pm, the weather turned very suddenly nasty and we were hit with a massive thunderstorm complete with violent hail. The thunderstorm hovered overhead for only a few minutes – but being rather exposed up at 11,200 feet – those few minutes passed extremely slowly.

Speed of Sound: When lightning strikes, you see the flash essentially immediately, since the speed of light is extremely high. But the speed of sound is slow, so you don’t hear the thunder until a few moments later. With sound moving at about 300 meters per second it is easy to figure out how close the lightning is striking. Ever since I was a kid, I’ve been counting the time between flash and bang to see how far the lightning really is. Every five seconds is a mile. When the time between flash and bang got to be about a second, (and the thunder was sounding awfully loud) I started worrying that we might be in a bit of trouble. Then it got down to half a second. --- then a bit less. Lightning striking within 100 meters from my tent. Yikes!

Electricity: It is hard to overstate the strength of lightning. The temperature of a lightning bolt can reach tens of thousands of degrees Celcius, and lightning hitting a tree can easily cause the tree to simply explode. The electrical power of a lightning bolt can reach a billion watts - on the order of the power output of a large nuclear power plant. And while the power of a single bolt remains “on” for only about a second, it can do an awful lot of damage in that time.

So, given the danger of lightning, what can you do to avoid getting zapped? The principle to keep in mind is to try to avoid having the lightning go through you. The best thing to do is to get inside a modern building or a metal vehicle. The metal in these objects is a great conductor (a so-called Faraday cage) and even if it does get hit, the electricity gets diverted around you. Unfortunately, when camping, this is not really an option. Here are some tips from the physicist for what one can do

(1) Don’t be the tallest thing around. (This should be obvious. You don’t want to be on the very top of a mountain).

(2) Don’t stand near the tallest thing around, like a tree, or anything sharp or metallic that might attract the lightning. (Lightning can strike the top of the tree, run down the tree and then jump to you)

(3) Don’t touch anything conductive like a metal fence, a long wet rope, or a large pool of water. The lightning can strike the object far away and then run along the conductive object to hit you.

(4) Touch the ground at only one point – i.e., keep your feet close together and do not lie down. The point of that when electricity is running through the ground away from a strike, you do not want the electricity to find you to be a more conductive path between two points than the ground is – thus going up from the ground, through you, and back down into the ground. Cows are often victims of lightning because their feet are so far apart.

(5) The thicker the insulation between you and the ground, the better. Wear your thick boots, stand on your backpack, or on a plastic ridge-rest or similar.

So if you are out camping, the best thing you can do in a lightning storm is to get away from tall trees in some low area (but not into the center of a flat field where you are the tallest thing around), stand on something insulating, put your feet together and crouch down.

Anyway, as the lightning storm quickly approached, I started putting on my hiking boots –preparing to follow my own advice. But in the dark, finding the headlamp, to then find my shoes was not so easy, and by the time I had them on, the storm was already receding, and I had already avoided getting zapped. Also, by that time, my tent was almost collapsing from the weight of the hail that had fallen on it. Once the hail stopped falling, I got out of my tent, looked around to see if anything was burning (nothing was), brushed off all of the hail from my tent, and climbed back into my sleeping bag to go to sleep.

Carissa reported that Lin’s first comment in the morning was “I hope Steve is still alive”


Jennie Guilfoyle said...

Thanks for posting. . . now where are the photos?

Steve said...

Photos coming soon.