20 January, 2003
Katabatic Wind Episode
I woke up this morning to the sound of a strong wind blowing and my tent sides flapping wildly. It was warm and cozy in my sleeping bag, so I found it really difficult to roll out and get moving. I suspected we might be having a katabatic wind episode, but they don't usually happen in the summer. The first thing I noticed was that the winds had shifted and were coming from the west and the polar plateau. This was the first time the winds had blown from that direction.
The weather was bad in McMurdo today, too, and at one point a Condition 1 was called there. This is dangerous weather including high winds, white-out conditions and extreme cold. All non-essential work outside is halted, and people are told to stay indoors. Remember though that McMurdo is about forty miles from where we are located, and it is across the Ross Sea. We often have very different weather than they are having. In the Dry Valleys we had high winds off and on, snow, and at one point rain! In all that I had read before coming here, the books said there had been little or no precipitation in the Dry Valleys, and virtually ALL of it was snow. We obviously experienced an odd weather day.
Katabatics are the strongest winds on the planet. They are caused by colder, denser air flowing down from the polar plateau to the coast. The pressure increases as the elevation decreases and the air warms. The winds are caused by the heavier air moving down from higher elevations. Normally these are dry winds because the warmer air holds more moisture, so our snow and rain were very odd in combination with the winds. By contrast, the winds on the polar plateau are usually very light.
After going to bed, we continued to get high winds and then about one AM the winds reached a fever pitch; probably about 40 MPH. Wrapped warmly in my sleeping bag, I mentally checked the large rocks my tent was tied to and wondered if they were big enough! Daryl told me he actually got up and packed his bags so if his tent blew away it would be easy to pick up his clothes! That was the voice of experience, I'd say. Suddenly the wind stopped and got eerily silent. I thought I might be able to sleep again, but soon enough the big blow started again.
Later today we experienced hail and a small amount of snow accumulation. I can't help but think the nematodes must be really happy with all this moisture. The "Wormherders" will be out tomorrow if the heloes are flying, so it will be interesting to see what they find. We noticed that the snow was blowing sideways, and when we looked at the "collars" around the worm farms, there was no snow inside. I wonder if the design needs to be adjusted to make the snow easier to catch when it blows sideways. Field science is a constant set of new questions.
Daryl, Louise, John, Karen and Jen. Thought you just might like to see our faces
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