A Beautiful Sunday Hike and my Introduction to Nacreous Clouds

Sunday turned out to be a beautiful day so a friend and I took a hike to Scott Base and beyond. I have never seen Mt. Erebus and Mt. Terror so clear. This was also my introduction to nacreous clouds that only occur this time of year.

The sign overlooking Scott Base.

Pressure ridges on the ice shelf looking like waves. Sunlight over the base of Mt. Terror.

Scott Base.

Mt. Erebus on the left and Mt. Terror on the right - named after the ships during the Antarctic Expedition of 1839-1843 led by the most experienced polar officer in the world - Sir James Clark Ross.

Nacreous clouds.

A relatively warm -19 degF. There wasn't any wind so it was a fine day. I imagine my family and friends in Florida would welcome a little coolness about now!

The nacreous clouds are also called polar stratospheric clouds at an altitude of 50,000-80,000 feet.

Due to their high altitude and the curvature of the earth's surface these clouds will receive sunlight from below the horizon and reflect it to the ground. 

Nacreous clouds only form at the polar regions but rarely in the north. The temperature must be extremely cold and dry. Since Antarctica is cold and also considered a desert they readily form this time of year.

They are also known as 'wave clouds'. I observed these clouds 'streaking' through the sky over a two hour period.

They are sometimes called 'mother of pearl' clouds as they blaze unbelievably bright with vivid and slowly shifting iridescent colors. They are filmy sheets slowly curling and uncurling, stretching and contracting in the semi-dark sky.

Their forms reveal the winds and waves of the stratosphere.

These clouds are made up of tiny ice crystals forming at around -124 degF. 

The iridescent colors are due to the crystals being in uniform shape and size and the cloud cover being thin.

The sun has to be just at the right angle below the horizon to cause diffraction and interference with the crystals to produce these beautiful colors.

The view from my dorm's back porch. Mt. Discovery in the background.

Winter Quarters Bay with the new ice pier. Hut Point in the middle.

                       

A video of Mt. Erebus and Mt. Terror.

Winfly

The first sunrise following the dark, cold winter is August 19. The following day the first Air Force C-17 Globemaster III is scheduled to land on the ice runway with passengers and cargo, ending nearly six months of isolation for the 153 people here in McMurdo. 


Seven flights are planned during the winter fly-in (Winfly) period, beginning on August 20th with the last flight August 27th. Winfly is the time between winter and the summer when additional support personnel, such as carpenters and cooks, arrive to prepare the station for the upcoming science field season. This will support the many field camp preparations. Along with that we will get fresh food and mail. September will find us in isolation again as the strongest winter storms move in. Summer flights will begin in October.

The planes will carry enough fuel so they won’t have to fill up at the airfield, meaning the engines will remain running while the military transport is on the ground for about an hour. The flight between New Zealand and Antarctica is about five hours each way.

The population will increase by about 300 but then about 30 winterovers will be leaving. The new arrivals will bring our first germs in 6 months so many of us will get sick. Some say to try and get sick right away so that it doesn't spoil your 'off the ice' plans.