My day with Mac

Joined: 23 Mar 2004 Posts: 72

Today we started getting to work early. We had to move the bridge so that we could do new tests in an undisturbed “clean” area of snow. It was a somewhat difficult task, because it first had to be hoisted high enough to get over the snow drifts. So some people took wood planks and used leverage to lift the ends of the bridge, while the rest of us kicked and shoveled snow underneath to get it up high enough to move it. Once the bridge was in place, we had to replace the “bonnet”- this is the plastic disc that holds all of the data sensors in place.

Once the bonnet was in place, I helped to put the thermocouplings in place. Thermocouplings are special thermometers that are made out of two types of metal.

This is me holding the thermocouplings before we inserted them in the snow.

I spent the rest of the day with Mac Cathles.

This is Mac. As you can see, he's kind of a crazy guy!

He is a research assistant for Cold Regions Research Engineering Laboratory. This is a division of the Army Corp. of engineers.
His part of the project focuses on the properties of snow. The goal of his study is to model how air flows through the firn probe (through the snow). The first thing we did was to dig a snow pit. We dug down 50cm with a saw. The snow is too tightly packed together to do it with a shovel. The we used the edge of the saw to smooth the inside walls of the pit. Once those walls were smooth, it was easy to see the layers of snow. By looking at these layers, you can see areas where the sun caused crystals to fuse together, forming ice. The ice layers are pretty thin. You can also see layers of different size grains, layers that are tighter packed than others, and you can tell when it was windy and snow had drifted in that area! It was a surprise for me that you could pretty easily see all these different things in a hole in the snow!

Next came a thermconductivity test. Thermal conductivity means how quickly heat moves through the snow. Sensors are placed in the snow. The two on the outsides are to measure what temperature the snow is under normal conditions. The middle sensor sends out heat, and measures how long it takes for that snow sample to get back to the normal temperature.

The next test we did was to take core samples of those layers of snow. Using a special tube that attaches to a drill, you can drill down and take a pretty undisturbed sample of the snow layers. These samples were then taken to a tent, where they were tested for permeability. Permeability is the ability of air to flow through the snow. It was surprising to me to discover that the samples taken from deeper in the pit were more permeable (allowed more air to flow through them) than the upper layers. Mack explained that this is because as the crystals of snow are covered by new layers, the lower layers are changed, and many times the crystals get bigger which means that the spaces between them are also bigger. Not what I expected!

Once that data was processed, we went back outside and did two more tests. One was to take snow crystal samples from each of the layers of snow and photograph them. This gives the researchers a better idea of the actual size of the grains in the particular layers. Since this pit was a relatively small one, most of the layers had quite small grains. In deeper pits, the crystals tend to be larger.

Next we began a stereology test. This test is quite complicated, and actually is not completed here at summit. A 3-dimensional chunk of snow is taken out of the pit and placed in a container. A chemical is added to the container that seeps into the air spaces in the snow sample. The chemical has a lower freezing temperature than water. This remains frozen, and is sent to another lab where it is put into a dry freezer, so that all of the water content sublimates (evaporates) away. All that is left is a mold showing the air spaces in the snow. A dye is then injected into the mold, and it fills the spaces where snow crystals used to be. After the dye hardens, the mold is then polished and cut into thin slices that the researchers can use to analyze snow crystals in much more detail than they can in the field.

The sun finally came out! It is amazing how beautiful this place is when the sun shines. Everything sparkles, and you can see “diamond dust” (small flakes of snow in the air) shining everywhere.

This is a picture of something called a sun dog. They form when ice crystals form high in the sky, and light relects through them. Its kind of like an arctic rainbow!

Tonight is “sushi night” at the big house. YIKES!!! Talk about grown-up food! You’d think they could ease me into it, and not make me jump to extreme grown-up food right away!!

My family got instant messaging today so that I can talk to them more often. I thought this was a really great idea- until, of course, my son Ian used it to let me know that they had MCDONALDS for lunch! How cruel!! Just wait ‘till I get home…..J

Nikki

Update: Late Saturday night: I ATE THE SUSHI!!! Ok, it wasn't the seafood kind, but it did have seaweed on it and I did eat it. I tried one bite of one, and they said if I could take a bite, I could eat a whole one. They made me eat it all at once. I totally felt like fear factor, but it felt strangely good to take that challenge.

I then, to wash down the disgusting taste of seaweed, felt compelled to make some liquid nitrogen ice cream. To make it, we used a regular icecream recipe, and instead of putting it in the freezer, we added liquid nitrogen to it, and it froze almost immediately!

As you can see, that was very cool!(and very, very yummy)