Today will be my last full day at the pole, if our flight is not cancelled. We are set to leave tomorrow, either very early in the morning or later during the day. We still do not have any certainty and need to remain flexible, as Antarctic travel depends strongly on weather plus a large number of other factors that are out of our reach.
Me doing measurements at an IceTop station.
At 9:00 am I went out again with Sam and Elisa to finish the snow coverage measurements that we had started two days ago. We did that in less than half an hour, and later on went on to make detailed measurements of snow cover from a random sample of four IceTop stations. The actual number of measurements was about 20 for each of the four IceTop locations sampled.
Doing more measurements. Credit: Sam De Ridder.
I asked Sam what his thoughts were concerning the data we were collecting, and he explained it as follows: "The winds at the South Pole create small hills and valleys of snow called 'sastrugi', which of course are sometimes seen on top of the IceTop tanks. Hence, we need to measure as the snow accumulates at several locations over a few sample IceTop tanks, and we also need to take these sastrugi formations into account when analyzing IceCube data."
The IceCube Laboratory (ICL).
The measurements we did left a number of holes, and the ice inside looked blue.
People have been asking about climate and weather conditions here at the South Pole, and I have been wanting to tackle this topic for a while. Here is a summary.
The South Pole experiences cold temperatures all year round primarily because of its southerly latitude. This occurs because at high latitudes—in both hemispheres—the Sun never reaches a considerable elevation above the horizon. But there are two other factors that need to be taken into consideration: the South Pole's location in the interior of the continent and away from the ocean, as well as its elevation of 2,800 meters above sea level. These two factors are not present at the North Pole, which explains why the North Pole never gets quite as cold as the South Pole.
The Sun keeps approximately the same elevation above the horizon—ranging between 18° to 23°—during most of December and January each year.
Solar halos are quite common at the South Pole. They form as sunlight travels through ice crystals in the atmosphere. Credit: Sam De Ridder.
Average temperatures at the South Pole are –26 °C (–15 °F) in January and –58 °C (–72 °F) in July. The all-time records are –12 °C (10 °F) and –83 °C (–117 °F). So, even at its warmest, the South Pole remains permanently below the freezing point.
The actual barometric (or physiological) elevation that is felt at the pole reaches an average of about 3,200 meters, which is significantly higher than its actual topographic elevation. This happens because—due to earth's rotation—the atmosphere is thinner at the poles.
The South Pole is also very dry, possibly the driest place on Earth. Since the air is so cold it can barely hold any moisture. When heated at room temperature—which is what we actually experience inside the station—relative humidity can go down to values around 1% or 2%.
Weather conditions at the South Pole can sometimes change rapidly, and a clear day can turn cloudy in a matter of minutes. I have seen this on a number of occasions during my stay at the pole.
Looking out through a window from A4 wing. Local time 12:01 am.
Same view, less than two hours later. Local time 1:55 am.
Before leaving I would like to share a pleasant surprise that I had. While browsing the books at the IceCube bookshelf I found a copy of 'Basic Physics of the Solar System', a 1961 textbook by Víctor M. Blanco and Sidney W. McCuskey. Although dated, the book is a classic from the early space age that was used to train a good number of early NASA specialists. Its co-author, Víctor M. Blanco is a renowned Puerto Rican astronomer who later on went to become director at Cerro Tololo Interamerican Observatory in Chile. It was a real treat being able to skim the book, as I had so many times seen references to it but had never had a chance to actually hold a copy. I would never have thought that I would end up finding such a book here, at the South Pole! Totally off-topic, but it was meaningful to me and I wanted to share it.
Basic Physics of the Solar System (1961), by Víctor M. Blanco and Sidney W. McCuskey.
Basic Physics of the Solar System (1961), by Víctor M. Blanco and Sidney W. McCuskey.
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