Monday, 2 January 2012
Halley is a remarkably sunny place - it actually gets more hours of sunshine than the UK, and of course most photographs tend to get taken on sunny days. When its cloudy or snowing then it gives a chance for the Antarctic Pixies to come out and play
Someone asked about how pilots can judge the ground, the answer is they need both horizontal and surface contrast. In the photo above you can't see the horizon which we call no horizontal contrast, you also can't see any details in the snow surface, so that's no surface contrast. When there is no horizontal or surface contrast you don't want to be landing planes! In fact even walking around can be tricky as you can trip over piles of snow without seeing them at all.
The photo below is still poor surface contrast (which is better than nil), but now has good horizontal contrast. The pilots land planes in those sort of conditions but only at sites they know are crevasse and sastrugi free. Sastrugi are irregularities in the surface of the snow caused by the wind.
Posted by Mike at 16:39