Posted by Cricket

Date: 1 Sept 2010
Sunrise: 9:36am
Sunset: 16:15pm
Temperature: -34C
Wind Speed: 10 knots
Temp with wind chill: -53C

The word “nacreous” stems from the Latin “nacre,” meaning mother of pearl.  Nacreous clouds are thin and transparent with a wave-like form, and were so named for their dazzling iridescent colors.  They appear most prominently at dawn and dusk, and have been an almost daily feature during the last couple weeks.

Nacreous clouds during sunrise © Antarctica New Zealand/Steven

In the late mornings they can be mixtures of rainbow colors, and by late afternoon, can change to waves of greens, blues and grays. 
Steven, our Scott Base science technician, explained that nacreous clouds are polar stratospheric clouds that only form in very cold polar regions and below –80C.  They exist well above our atmosphere at heights of 15-25km in the stratosphere, and being so high up, they appear stationary.  They gain their colors by reflecting sunlight coming from below the horizon, and so, are a skyline feature unique to this time of year.  They are a reminder of larger forces at play, and are associated with the chemical reactions that cause ozone depletion.

Nacreous clouds during the afternoon © AHT/Cricket

To those wintering over in Antarctica, nacreous clouds must seem like fireworks after a 4-month-long term of darkness.  Seeing them does feel like a celebration, and their presence fosters joy and conversation.  Summer is coming quickly here and every day we have longer periods of daylight – a stark contrast to the almost constant darkness that we encountered upon our arrival several weeks ago.  As the sun reaches higher in the sky, our time for sighting nacreous clouds draws to a close.  Their appearance has been the best welcome to this fantastic landscape.

Posted by Nicola

Date:                  19 August 2010
Temperature:      -29c
Wind Speed:       10 knots
Temp with wind chill: 45c
Sunrise:              The first sunrise 12.26
Sunset:               13.30

With just a couple of days to go before we leave Scott Base, Antarctica, we are pleased to have come through the winter with just a couple of cases of frost-nip. We have all experienced the extreme pain of warming up fingers frozen whilst trying to operate cameras in thin gloves, but the polar clothing and toe and hand-warmers have kept us toasty.

The hut at Cape Royds with Erebus in the background © AHT/N Dunn

Frostbite was a common complaint of the early explorers whose exposed skin, toes and fingers would turn black and swell with large blisters, the pain must have been excruciating. In the lab this week we had an artefact, known as ‘Brocklehurst’s leg protector’ which reminded us of how lucky we have been.

Sir Phillip Brocklehurst was the 19 year old assistant geologist on Shackleton’s 1907-09 expedition and part of the first team to climb Mount Erebus. The ascent was made in improvised climbing boots made of ski boots with nails hammered into the soles. On the treacherous slopes they survived a 36-hour blizzard before continuing the climb in intense cold, Brocklehurst still in his ski boots as he didn’t think it necessary to change into the better insulated ‘finnesko’ boots of reindeer skin. After nine hours both his big toes were black and frostbitten and he remained in the tent whilst the others made it to the summit.

Brocklehurst’s leg protector made from painted steel rods bound with paper strips © AHT

Later one of his toes was amputated by Marshall (the expedition surgeon and cartographer) with Mackay (expedition doctor) acting as anaesthetist. The cold meant that the wounds healed slowly and as he recovered in Shackleton’s bed the metal cage protected the damaged foot from the weight of the blankets. Thank goodness for toe warmers!

I have just finished conserving a group of tins from Captain Scott’s hut at Cape Evans which has been quite challenging over the last few weeks. With so many objects containing paper elements it has not been possible for George, our paper conservator, to conserve them all, so I have had the opportunity to learn new paper conservation skills from her.

Griffith & McAlister made dried food products like tapioca, lentils and macaroni, packed in distinctive square blue tins, wrapped in coarse paper and tied with string. Removing the wrappers can be a daunting process as the corroding iron from the tins is acidic and impregnates the paper, causing the wrapper to become very brittle.