Diamond Dust and other weather

The weather here at Halley is a constant surprise.  We get a weekly weather forecast, but it changes from moment to moment.and often the only way to check what the weather is doing is the old fashioned way - you look out of the window.

Today the wind is blowing at around 20 knots.  This kind of wind speed will pick up lying snow and blow it around to just above head height, reducing visibility and creating unexpected obstacles where there were none before.  The vehicle guys are kept busy on Snow Management and if you venture outside you keep an eye on where you are going.

Last week we had a weather phenomenon called Diamond Dust, or, more prosaically, clear air precipitation.  The sun shines brilliantly down, there is not a cloud in the sky, the snow on the ground glitters like a mad thing - and so does the air.  Everywhere you look you see the air sparkling and flashing with tiny pieces of light; it is the most amazing thing you have ever seen.

The picture above has managed to capture a flavour of this beautiful effect - apologies for the subject matter, although these are truly unique Antarctic oil drums - you can see the sparkle and glitter of the snow and the air.

Sadly we don't get diamond dust every day, but on sunny days the snow gleams and sparkles for miles and on cloudy days you can get what is called low contrast.  This is where the snow stretches all around, a flat, featureless field of white.  You stare at it in vain, knowing it rises and falls in humps and bumps ahead of you but completely unable to see it, even when you are right on top of it.  The sky changes colour too, when there are clouds they reflect the sea on the horizon and look a dark, forbidding bluey grey compared to the whiteness of the cloud above the snow.  If there are no clouds the sky is pale blue along the horizon, darkening to a bright, intense blue above. 

I see something different every day and each day brings something new to wonder at.  Last night I watched from the window as the wind increased in strength and sent plumes of snow snaking across the surface, hugging the contours as they went.  This morning I gazed out of my window to a changed landscape where the winds had increased during the night and blown the snow around, altering the way things had looked the evening before.  This afternoon will probably be different again.

There is a saying here - if you don't like the weather at Halley, wait five minutes.