7 August, 2000

August 7 , 2000

Matanuska Glacier, Alaska

Today has been an absolutely beautiful day here with sunny skies and warm temperatures. Unfortunately the work for the day was to analyze the samples collected yesterday. It would have been a good day to be out on the ice and not stuck in camp. At any rate we got good results once again and it allows us to compare what’s going on during high and low flow. Our only other experiment that successfully yielded data for both M-1 and Mega Vent simultaneously was Dye Experiment #4. In both experiments the dye appears at Mega Vent just before arriving at M-1 despite the fact that M-1 is actually closer to the moulin. It also turns out that the concentrations at M-1 are always lower than those at Mega Vent. We are discussing possible explanations for these results.

Late last night the sky cleared up and I again watched for a possible display of the Northern Lights. And once again I had to go to sleep disappointed that there was no show. It was still an enjoyable evening to be out and for the first time I was able to see the Big Dipper in the sky. As I expected it was much higher in the sky than what I’m used to at home due to the tilt of the earth and the more northern latitude. I had been wondering for about a week whether or not a certain bright star in the north was the North Star. I doubted that it was because it seemed too low in the sky. But I thought perhaps the Talkeetna Mountains to the north gave the illusion of the star being low. With the Dipper as a reference I was able to see that this bright star was not the North Star. The North Star was actually very high in the sky. I also noticed numerous satellites zooming by as well.

The Northern Lights are also known as the Aurora Borealis, a name first used by Galileo in 1619 to suggest the likeness to an early dawn in the northern sky. He wrongly thought that the aurora was caused by sunlight reflecting from the high atmosphere. It is actually a light source created high in the atmosphere. It is a glow given off by the atoms and molecules when they are struck by charged parcticles, mostly electrons and protons, that originate on the sun. Moving charged parcticles are deflected by magnetic fields and the earth’s field tends to guide these parcticles toward the poles where they enter the atmosphere and make it glow. For this reason the displays are more common near the polar regions. In the southern hemisphere this glow is called the Southern Lights or Aurora Australis.

There are many familiar examples of light being produced by the flow of charged parcticles through gases. Lightning or sparks from static electricity discharges are simple, natural examples of this. Fluorescent and neon lights give off their light when electricity (electron flow) passes through the gas filled tubes. A television set works because electrons are guided toward certain locations on the TV screen where they cause substances in the screen called phosphors to glow. The picture tube has plates in the back that produce changing magnetic fields which cause the path of the electrons to change as well. The result is the constantly changing scene on the TV screen. If you have a black and white TV just pass a magnet over the surface of the screen and watch what happens. DO NOT try this on a color set or computer monitor as it can cause permanent damage to the color display.

I have seen the Northern Lights on two occasions in my lifetime. Several years ago I watched them in the Boundary Waters Canoe Area in northern Minnesota. I also happened to see them at home in Indiana one early evening a few years ago. I’m still hopeful that one of these remaining nights will offer an opportunity to watch this amazing phenomenon.

Marvin Giesting

Beautiful sunny mornings such as today provide great views up Glacier Creek directly across from camp.

Graph comparing the results of a low flow test (Experiment 4) and high flow (Experiment 6). The interesting things we see are that: dye appears at Mega Vent before M-1 in spite of being farther from the moulin; concentrations at Mega are always higher than M-1; dye appears more quickly at high flow; and concentrations are lower at high flow. Some of this is simple to interpret but it also raises questions too. The area under each curve is an approximation of the amount of dye that passes through. At high flow where does a lot of the dye go? Apparently we've answered a question we had earlier as to whether or not other conduits are filled when the water rises.