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Norwegian-American Scientific Traverse of East Antarctica

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Windchill

by Stein Tronstad — sist endret 22.02.2009 - 23:01

In a flat calm and with the sun high in the sky, -30 C (-22 F) can feel quite balmy and even -40 C (-40 F) can be tolerable. A gale can turn those 40 degrees into a savage beast.

Location: ”NUS08-7”, 74º 07’ S, 1º 36’ E, 2700 metres a.s.l.
Weather: Clear, -42 C, wind 28 kts

We have had the somewhat dubious pleasure of facing that beast today.  For those of us working outside, the term “windchill” took on a very concrete meaning. This is a calculated temperature figure, intended to show the combined effect of temperature and wind on exposed skin.  More wind means that more cold air passes by the skin, and thus more body heat is transported away than when the air is still. The windchill figure aims to say what air temperature the cooling effect would correspond to if experienced on a day with no wind.   Today the air temperature of -42 C and the gale force wind combined to give a windchill of -65 C, meaning that the conditions were just as chilling as a day with -65 C (-86 F) and no wind. In such conditions any exposed skin will be frostbitten within a few minutes, or even seconds.  Full coverage of all body parts, even the face, is required when working outside.

The vehicles were also affected quite a bit.  With the wind came persistent snowdrift, and the gale pushed the snow into any open gap, crack and crevice – including the air intakes and exhaust pipes of the Webasto heaters. Being unable to preheat the engines in the morning, we had to employ industrial heaters and wind breaks to get anywhere.  Only after 8 hours of work did we have all four vehicles up and running, and thus our departure from science site 7 was delayed by almost a full day.  (The science summary from site 7 was also affected, but you will have it tomorrow.)

To make up for lost time and to avoid stopping the engines in this unabated gale, we have been driving through the night till Thursday.  It was the first on the traverse that felt like a real night – not very dark, as the sun was barely below the horizon for four hours, but rather a palette of pale pastels, with its own dreamlike splendour.  We have seen the winter cloak of the ice cap, and it is time for us to go down.


11feb

Engine revival in windchill -65.  Photo: Stein Tronstad/NPI

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